newLISP v.10.7.0 Manual and Reference

newLISP focuses on the core components of Lisp: lists, symbols, and lambda expressions. To these, newLISP adds arrays, implicit indexing on lists and arrays, and dynamic and lexical scoping. Lexical scoping is implemented using separate namespaces called contexts.

The result is an easier-to-learn Lisp that is even smaller than most Scheme implementations, but which still has about 350 built-in functions. Not much over 200k in size on BSD systems, newLISP is built for high portability using only the most common Unix system C-libraries. It loads quickly and has a small memory footprint. newLISP is as fast or faster than other popular scripting languages and uses very few resources.

Both built-in and user-defined functions, along with variables, share the same global symbol tree and are manipulated by the same functions. Lambda expressions and user-defined functions can be handled like any other list expression.

newLISP is dynamically scoped inside lexically separated contexts (namespaces). Contexts in newLISP are used for multiple purposes. They allow (1) partitioning of programs into modules, (2) the definition of Classes in FOOP (Functional Object Oriented Programming), (3) the definition of functions with state and (4) the creation of Hash trees for associative key → value storage.

newLISP's efficient red-black tree implementation can handle millions of symbols in namespaces or hashes without degrading performance.

newLISP allocates and reclaims memory automatically, without using traditional asynchronous garbage collection. All objects — except for contexts, built-in primitives, and symbols — are passed by value and are referenced only once. Upon creation objects are scheduled for delayed deletion and Lisp cells are recycled for newly created objects. This results in predictable processing times without the pauses found in traditional garbage collection. newLISP's unique automatic memory management makes it the fastest interactive Lisp available. More than any other Lisp, it implements the data equals program paradigm and full self reflection.

Many of newLISP's built-in functions are polymorphic and accept a variety of data types and optional parameters. This greatly reduces the number of functions and syntactic forms necessary to learn and implement. High-level functions are available for string and list processing, financial math, statistics, and Artificial Intelligence applications.

newLISP has functions to modify, insert, or delete elements inside complex nested lists or multi-dimensional array structures.

Because strings can contain null characters in newLISP, they can be used to process binary data with most string manipulating functions.

newLISP can also be extended with a shared library interface to import functions that access data in foreign binary data structures. The distribution contains modules for importing popular C-library APIs.

newLISP's HTTP, TCP/IP, and UDP socket interfaces make it easy to write distributed networked applications. Its built-in XML interface, along with its text-processing features — Perl Compatible Regular Expressions (PCRE) and text-parsing functions — make newLISP a useful tool for CGI processing. The source distribution includes examples of HTML forms processing. newLISP can be run a as a CGI capable web server using its built-in http mode option.

newLISP has built-in support for distributed processing on networks and parallel, concurrent processing on the same CPU with one or more processing cores.

The source distribution can be compiled for Linux, Mac OS X/Darwin, BSDs, many other Unix flavors and MS Windows. newLISP can be compiled as a 64-bit LP64 application for full 64-bit memory addressing.

Since version 10.5.7, newLISP also can be compiled to JavaScript and run in a web browser.

newLISP-GS

newLISP-GS comprises a graphical user interface (GUI) and library server. The GUI front-end is written in newLISP, whereas the library server is Java based and uses the standard Java runtime environment installed on all Windows and Mac OS X platforms. Applications built with newLISP-GS can have the host operating system's native look and feel. Interfaces to GTK, Tcl/Tk and OpenGL graphics libraries are also available.

newLISP and Java are available for most operating systems. This makes newLISP-GS a platform-independent solution for writing GUI applications.

Licensing

2. Deprecated functions and future changes

Since version 10.3.0 newLISP can switch between IPv4 and IPv6 modes during run-time using the new net-ipv function. The -6 commandline option can be used to start newLISP in IPv6 mode. After transition to IPv6 the -6 commandline switch will be changed to -4 for starting up in IPv4 mode.

The old writing parse-date of date-parse is still recognized but deprecated since version 10.3.0. The old writing will be removed in a future version.

Since version 10.4.2 if-not is deprecated and will be removed in a future version.

Since version 10.4.6 newLISP has a built-in function json-parse for translating JSON data into S-expressions. The module file json.lsp is removed from the distribution.

Since version 10.4.8 newLISP has built-in support for unlimited precision integers. This makes the GNU GMP module gmp.lsp obsolete.

3. Interactive Lisp mode

The best way to experience Lisp and experiment with it, is using interactive mode in a terminal window or operating system command shell. Since version 10.3, newLISP's read-eval-print-loop (REPL) accepts multi-line statements.

To enter a multi-line statement hit the [enter] key on an empty line after the system prompt. To exit multi-line mode, hit the [enter] key again on an empty line. In the following example computer output is shown in bold letters:

Note, that multi-line mode is only possible in an OS command terminal window or command shell. The monitor window in the Java based newLISP-GS IDE will not accept multi-line statements.

Interactive Lisp mode can accept operating system shell commands. To hit an OS command enter the '!' character right after the prompt, immediately followed by the shell command:

In the example a ls shell command is entered to show HTML files in the current directory. On MS Windows a dir command could be used in the same fashion.

The Vi editor will open to edit the program "foo.lsp". After leaving the editor the program could be run using a load statement:

The program foo.lsp is now run. This mode using '!' can also be used from the newLISP-GS IDE.

When using a Unix terminal or command shell, tab-expansion for built-in newLISP functions can be used:

After entering the characters (pri hit the [tab] key once to show all the built-in functions starting with the same characters. When hitting [tab] twice before a function name has started, all built-in function names will be displayed.

On most Unix, parenthesis matching can be enabled on the commandline by including the following line in the file .inputrc in the home directory:

Not all systems have a version of libreadline advanced enough for this to work.

4. Command-line options, startup and directories

Command line help summary

When starting newLISP from the command-line several switches and options and source files can be specified. Executing:

Before or after the command-line switches, files to load and execute can be specified. If a newLISP executable program is followed by parameters, the program must finish with and (exit) statement, else newLISP will take command-line parameters as additional newLISP scripts to be loaded and executed.

Specifying files as URLs

newLISP will load and execute files specified on the command-line. Files are specified with either their pathname or a file:// URL on the local file system or with a http:// URL on remote file systems running an HTTP server. That HTTP server can be newLISP running in HTTP server mode.

No loading of init.lsp

This option suppresses loading of any present initialization file init.lsp or .init.lsp. In order to work, this must be the first option specified:

Stack size

The above examples show starting newLISP with different stack sizes using the -s option, as well as loading one or more newLISP source files and loading files specified by an URL. When no stack size is specified, the stack defaults to 2048. Per stack position about 80 bytes of memory are preallocated.

Maximum memory usage

This example limits newLISP cell memory to 128 megabytes. In 32-bit newLISP, each Lisp cell consumes 16 bytes, so the argument 128 would represent a maximum of 8,388,608 newLISP cells. This information is returned by sys-info as the list's second element. Although Lisp cell memory is not the only memory consumed by newLISP, it is a good estimate of overall dynamic memory usage.

Direct execution mode

The expression enclosed in quotation marks is evaluated, and the result is printed to standard out (STDOUT). In most Unix system shells, single quotes can also be used as command string delimiters. Note that there is a space between -e and the quoted command string.

Logging I/O

In any mode, newLISP can write a log when started with the -l or -L option. Depending on the mode newLISP is running, different output is written to the log file. Both options always must specify the path of a log-file. The path may be a relative path and can be either attached or detached to the -l or -L option. If the file does not exist, it is created when the first logging output is written.

logging mode	command-line and net-eval with `-c`	HTTP server with `-http`
`newlisp -l`	log only input and network connections	log only network connections
`newlisp -L`	log also newLISP output (w/o prompts)	log also HTTP requests

All logging output is written to the file specified after the -l or -L option.

Specifying the working directory

The -w option specifies the initial working directory for newLISP after startup:

All file requests without a directory path will now be directed to the path specified with the -w option.

Suppressing the prompt and HTTP processing

Listen and connection messages are suppressed if logging is not enabled. The -c option is useful when controlling newLISP from other programs; it is mandatory when setting it up as a net-eval server.

The -c option also enables newLISP server nodes to answer HTTP GET, PUT, POST and DELETE requests, as well as perform CGI processing. Using the -c option, together with the -w and -d options, newLISP can serve as a standalone httpd webserver:

When running newLISP as a inetd or xinetd enabled server on Unix machines, use:

In -c mode, newLISP processes command-line requests as well as HTTP and net-eval requests. Running newLISP in this mode is only recommended on a machine behind a firewall. This mode should not be run on machines open and accessible through the Internet. To suppress the processing of net-eval and command-line–like requests, use the safer -http option.

Forcing prompts in pipe I/O mode

A capital C forces prompts when running newLISP in pipe I/O mode inside the Emacs editor:

newLISP as a TCP/IP server

This example shows how newLISP can listen for commands on a TCP/IP socket connection. In this case, standard I/O is redirected to the port specified with the -p option. some.lsp is an optional file loaded during startup, before listening for a connection begins.

The -p option is mainly used to control newLISP from another application, such as a newLISP GUI front-end or a program written in another language. As soon as the controlling client closes the connection, newLISP will exit.

A telnet application can be used to test running newLISP as a server. First enter:

The & indicates to a Unix shell to run the process in the background. On Windows, start the server process without the & in the foreground and open a second command window for the telnet application. Now connect with a telnet:

If connected, the newLISP sign-on banner and prompt appear. Instead of 4711, any other port number could be used.

TCP/IP daemon mode

When the connection to the client is closed in -p mode, newLISP exits. To avoid this, use the -d option instead of the -p option:

This works like the -p option, but newLISP does not exit after a connection closes. Instead, it stays in memory, listening for a new connection and preserving its state. An exit issued from a client application closes the network connection, and the newLISP daemon remains resident, waiting for a new connection. Any port number could be used in place of 4711.

After each transaction, when a connection closes, newLISP will go through a reset process, reinitialize stack and signals and go to the MAIN context. Only the contents of program and variable symbols will be preserved when running a stateful server.

When running in -p or -d mode, the opening and closing tags [cmd] and [/cmd] must be used to enclose multiline statements. They must each appear on separate lines. This makes it possible to transfer larger portions of code from controlling applications.

The following variant of the -d mode is frequently used in a distributed computing environment, together with net-eval on the client side:

The -c spec suppresses prompts, making this mode suitable for receiving requests from the net-eval function.

newLISP server nodes running will also answer HTTP GET, PUT and DELETE requests. This can be used to retrieve and store files with get-url, put-url, delete-url, read-file, write-file and append-file, or to load and save programs using load and save from and to remote server nodes. See the chapters for the -c and -http options for more details.

HTTP-only server mode

newLISP can be limited to HTTP processing using the -http option. With this mode, a secure httpd web server daemon can be configured:

When running newLISP as an inetd or xinetd-enabled server on Unix machines, use:

To further enhance security and HTTP processing, load a program during startup when using this mode:

The file httpd-conf.lsp contains a command-event function configuring a user-defined function to analyze, filter and translate requests. See the reference for this function for a working example.

In the HTTP modes enabled by either -c or -http, the following file types are recognized, and a correctly formatted Content-Type: header is sent back:

file extension	media type
.avi	video/x-msvideo
.css	text/css
.gif	image/gif
.htm	text/htm
.html	text/html
.jpg	image/jpg
.js	application/javascript
.mov	video/quicktime
.mp3	audio/mpeg
.mpg	video/mpeg
.pdf	application/pdf
.png	image/png
.wav	audio/x-wav
.zip	application/zip
any other	text/plain

To serve CGI, HTTP server mode needs a /tmp directory on Unix-like platforms or a C:\tmp directory on MS Windows. newLISP can process GET, PUT, POST and DELETE requests and create custom response headers. CGI files must have the extension .cgi and have executable permission on Unix. More information about CGI processing for newLISP server modes can be found in the document Code Patterns in newLISP.

In both server modes -c and -http the environment variables DOCUMENT_ROOT, HTTP_HOST, REMOTE_ADDR, REQUEST_METHOD, SERVER_SOFTWARE and QUERY_STRING are set. The variables CONTENT_TYPE, CONTENT_LENGTH, HTTP_HOST, HTTP_USER_AGENT and HTTP_COOKIE are also set, if present in the HTTP header sent by the client.

Local domain Unix socket server

Instead of a port, a local domain Unix socket path can be specified in the -d or -p server modes.

Local domain socket connections are much faster than normal TCP/IP network connections and preferred for communications between processes on the same local file system in distributed applications. This mode is not available on MS Windows.

Connection timeout

Specifies a connection timeout when running in -p or -d demon mode. A newLISP Server will disconnect when no further input is read after accepting a client connection. The timeout is specified in micro seconds:

inetd daemon mode

The inetd server running on virtually all Linux/Unix OSes can function as a proxy for newLISP. The server accepts TCP/IP or UDP connections and passes on requests via standard I/O to newLISP. inetd starts a newLISP process for each client connection. When a client disconnects, the connection is closed and the newLISP process exits.

inetd and newLISP together can handle multiple connections efficiently because of newLISP's small memory footprint, fast executable, and short program load times. When working with net-eval, this mode is preferred for efficiently handling multiple requests in a distributed computing environment.

Two files must be configured: services and inetd.conf. Both are ASCII-editable and can usually be found at /etc/services and /etc/inetd.conf.

Instead of root, another user and optional group can be specified. For details, see the Unix man page for inetd.

On Mac OS X and some Unix systems, xinetd can be used instead of inetd. Save the following to a file named net-eval in the /etc/xinetd.d/ directory:

For security reasons, root should be changed to a different user and file permissions of the www document directory adjusted accordingly. The only_from spec can be left out to permit remote access.

See the man pages for xinetd and xinetd.conf for other configuration options.

After configuring the daemon, inetd or xinetd must be restarted to allow the new or changed configuration files to be read:

newLISP handles everything as if the input were being entered on a newLISP command-line without a prompt. To test the inetd setup, the telnet program can be used:

newLISP expressions can now be entered, and inetd will automatically handle the startup and communications of a newLISP process. Multiline expressions can be entered by bracketing them with [cmd] and [/cmd] tags, each on separate lines.

newLISP server nodes answer HTTP GET and PUT requests. This can be used to retrieve and store files with get-url, put-url, read-file, write-file and append-file, or to load and save programs using load and save from and to remote server nodes.

Linking a source file with newLISP for a new executable

Source code and the newLISP executable can be linked together to build a self-contained application by using the -x command line flag.

The program uppercase.lsp takes the first word on the command-line and converts it to uppercase.

newLISP will find a newLISP executable in the execution path of the environment and link a copy of the source code.

Note that neither one of the initialization files init.lsp nor .init.lsp is loaded during startup of linked programs.

5. Startup, directories, environment

Environment variable NEWLISPDIR

During startup, newLISP sets the environment variable NEWLISPDIR, if it is not set already. On Linux, BSDs, Mac OS X and other Unixes the variable is set to /usr/share/newlisp. On MS Windows the variable is set to %PROGRAMFILES%/newlisp.

The environment variable NEWLISPDIR is useful when loading files installed with newLISP:

A predefined function module can be used to shorten the second statement loading from the modules/ directory:

The initialization file init.lsp

Before loading any files specified on the command-line, and before the banner and prompt are shown. newLISP tries to load a file .init.lsp from the home directory of the user starting newLISP. On Mac OS X, Linux and other Unix the home directory is found in the HOME environment variable. On MS Windows the directory name is contained in the USERPROFILE or DOCUMENT_ROOT environment variable.

If a .init.lsp cannot be found in the home directory newLISP tries to load the file init.lsp from the directory found in the environment variable NEWLISPDIR.

When newLISP is run as a shared library, an initialization file is looked for in the environment variable NEWLISPLIB_INIT. The full path-name of the initialization file must be specified. If NEWLISPLIB_INIT is not defined, no initialization file will be loaded by the library module.

Although newLISP does not require init.lsp to run, it is convenient for defining functions and system-wide variables.

Note that neither one of the initialization files init.lsp nor .init.lsp is loaded during startup of linked programs.

Directories on Linux, BSD, Mac OS X and other Unix

The directory /usr/share/newlisp/modules contains modules with useful functions POP3 mail, etc. The directory /usr/share/newlisp/guiserver contains sample programs for writing GUI applications with newLISP-GS. The directory /usr/share/doc/newlisp/ contains documentation in HTML format.

Directories on MS Windows

On MS Windows systems, all files are installed in the default directory %PROGRAMFILES%\newlisp. PROGRAMFILES is a MS Windows environment variable that resolves to C:\Program files\newlisp\ in English language installations. The subdirectories %PROGRAMFILES%\newlisp\modules and %PROGRAMFILES%\newlisp\guiserver contain modules for interfacing to external libraries and sample programs written for newLISP-GS.

6. Extending newLISP with shared libraries

Many shared libraries on Unix and MS Windows systems can be used to extend newLISP's functionality. Examples are libraries for writing graphical user interfaces, libraries for encryption or decryption and libraries for accessing databases.

The function import is used to import functions from external libraries. The function callback is used to register callback functions in external libraries. Other functions like pack, unpack, get-char, get-string, get-int and get-long exist to facilitate formatting input and output to and from imported library functions. The fucntion cpymem allows direct memory-to-memory copy specifying addresses.

Most of the functions used when writing APIs for share libraries can cause newLISP to segfault when not used correctly. The reference documentation marks these functions with a ⚠ character linking to this chapter.

7. newLISP as a shared library

newLISP as C library

newLISP can be compiled as a shared C library. On Linux, BSDs and other Unix flavors the library is called newlisp.so. On Windows it is called newlisp.dll and newlisp.dylib on Mac OS X. A newLISP shared library is used like any other shared library.

The main function to import is newlispEvalStr. Like eval-string, this function takes a string containing a newLISP expression and stores the result in a string address. The result can be retrieved using get-string. The returned string is formatted like output from a command-line session. It contains terminating line-feed characters, but not the prompt string.

When calling newlispEvalStr, output normally directed to the console (e.g. return values or print statements) is returned in the form of an integer string pointer. The output can be accessed by passing this pointer to the get-string function. To silence the output from return values, use the silent function.

To enable stdio on the console, import the function newlispLibConsole and call it with a parameter of 1 for enabling I/O on the console with stdin and stdout.

newLISP as a JavaScript library

Since version 10.5.7, newLISP can be compiled to JavaScript using the Emscripten toolset. The library can be used to run newLISP clientr-side in a web browser, just like JavaScript or HTML. An HTML page can host both, newLISP code and JavaScript code together. Both languages can call each other. For more information see the newlisp-js-x.x.x.zip distribution package which contains the library newlisp-js-lib.js, documentaion and example applications. A small newLISP development environment hosted in a browser can also be accessed here: newlisp-js The application contains links to another example application, documentation and a download link for the whole package.

8. Evaluating newLISP expressions

The following is a short introduction to newLISP statement evaluation and the role of integer and floating point arithmetic in newLISP.

Top-level expressions are evaluated when using the load function or when entering expressions in console mode on the command-line.

Interactive multiline expressions

Multiline expressions can be entered by entering an empty line first. Once in multiline mode, another empty line returns from entry mode and evaluates the statement(s) entered (ouput in boldface):

Entering multiline mode by hitting the enter key on an empty line suppresses the prompt. Entering another empty line will leave the multiline mode and evaluate expressions.

As an alternativo to entering empty lines, the [cmd] and [/cmd] tags are used, each entered on separate lines. This mode is used by some interactive IDEs controlling newLISP and internally by the net-eval function. The [cmd] and [/cmd] tags must also be used in the console part of the newLISP-GS Java IDE.

Integer, floating point data and operators

newLISP functions and operators accept integer and floating point numbers, converting them into the needed format. For example, a bit-manipulating operator converts a floating point number into an integer by omitting the fractional part. In the same fashion, a trigonometric function will internally convert an integer into a floating point number before performing its calculation.

The symbol operators (+ - * / % $ ~ | ^ << >>) return values of type integer. Functions and operators named with a word instead of a symbol (e.g., add rather than +) return floating point numbers. Integer operators truncate floating point numbers to integers, discarding the fractional parts.

newLISP has two types of basic arithmetic operators: integer (+ - * /) and floating point (add sub mul div). The arithmetic functions convert their arguments into types compatible with the function's own type: integer function arguments into integers, floating point function arguments into floating points. To make newLISP behave more like other scripting languages, the integer operators +, -, *, and / can be redefined to perform the floating point operators add, sub, mul, and div:

Now the common arithmetic operators +, -, *, and / accept both integer and floating point numbers and return floating point results.

Care must be taken when importing from libraries that use functions expecting integers. After redefining +, -, *, and /, a double floating point number may be unintentionally passed to an imported function instead of an integer. In this case, floating point numbers can be converted into integers by using the function int. Likewise, integers can be transformed into floating point numbers using the float function:

Some of the modules shipping with newLISP are written assuming the default implementations of +, -, *, and /. This gives imported library functions maximum speed when performing address calculations.

The newLISP preference is to leave +, -, *, and / defined as integer operators and use add, sub, mul, and div when explicitly required. Since version 8.9.7, integer operations in newLISP are 64 bit operations, whereas 64 bit double floating point numbers offer only 52 bits of resolution in the integer part of the number.

Big integer, multiple precision arithmetic

function	description
+ - * / ++ -- %	arithmetic operators
< > = <= >= !=	logical operators
abs	returns the absolute value of a number
gcd	calculates the greatest common divisor of a group of integers
even?	checks the parity of an integer number
odd?	checks the parity of an integer number
number?	checks if an expression is a float or an integer
zero?	checks if an expression is 0 or 0.0

If the first argument in any of these operators and functions is a big integer, the calculation performed will be in big integer mode. In the Function Reference section of this manual these are marked with a bigint suffix.

Literal integer values greater than 9223372036854775807 or smaller than -9223372036854775808, or integers with an appended letter L, will be converted and processed in big integer mode. The function bigint can be used to convert from integer, float or string format to big integer. The predicate bigint? checks for big integer type.

When doing mixed integer / big integer arithmetic, the first argument should be a big integer to avoid erratic behaviour.

Under most circumstances mixing float, integers and big integers is transparent. Functions automatically do conversions when needed on the second argument. The overflow behavior when using normal integers and floats only, has not changed from newLISP versions previous to 10.5.0.

Evaluation rules and data types

Evaluate expressions by entering and editing them on the command-line. More complicated programs can be entered using editors like Emacs and VI, which have modes to show matching parentheses while typing. Load a saved file back into a console session by using the load function.

A line comment begins with a ; (semicolon) or a # (number sign) and extends to the end of the line. newLISP ignores this line during evaluation. The # is useful when using newLISP as a scripting language in Linux/Unix environments, where the # is commonly used as a line comment in scripts and shells.

When evaluation occurs from the command-line, the result is printed to the console window.

The following examples can be entered on the command-line by typing the code to the left of the → symbol. The result that appears on the next line should match the code to the right of the → symbol.

Integers, big integers and floating point numbers evaluate to themselves:

Integers are 64-bit including the sign bit. Valid integers are numbers between -9,223,372,036,854,775,808 and +9,223,372,036,854,775,807. Larger numbers converted from floating point numbers are truncated to one of the two limits. Integers internal to newLISP, which are limited to 32-bit numbers, overflow to either +2,147,483,647 or -2,147,483,648.

Floating point numbers are IEEE 754 64-bit doubles. Unsigned numbers up to 18,446,744,073,709,551,615 can be displayed using special formatting characters for format.

Big integers are of unlimited precision and only limited in size by memory. The memory requirement of a big integer is:

Where digits are decimal digits, bytes are 8 bits and ceil is the ceiling function rounding up to the next integer.

Strings may contain null characters and can have different delimiters. They evaluate to themselves.

Strings delimited by " (double quotes) will also process the following characters escaped with a \ (backslash):

character	description
`\"`	for a double quote inside a quoted string
`\n`	for a line-feed character (ASCII 10)
`\r`	for a return character (ASCII 13)
`\b`	for a backspace BS character (ASCII 8)
`\t`	for a TAB character (ASCII 9)
`\f`	for a formfeed FF character (ASCII 12)
`\nnn`	for a three-digit ASCII number (nnn format between 000 and 255)
`\xnn`	for a two-digit-hex ASCII number (xnn format between x00 and xff)
`\unnnn`	for a unicode character encoded in the four `nnnn` hexadecimal digits. newLISP will translate this to a UTF8 character in the UTF8 enabled versions of newLISP.
`\\`	for the backslash character (ASCII 92) itself

Quoted strings cannot exceed 2,047 characters. Longer strings should use the [text] and [/text] tag delimiters. newLISP automatically uses these tags for string output longer than 2,047 characters.

The { (left curly bracket), } (right curly bracket), and [text], [/text] delimiters do not perform escape character processing.

In the above example, the number between the < > (angle brackets) is the hexadecimal memory address (machine-dependent) of the add function. It is displayed when printing a built-in primitive.

A single quote is often used to protect an expression from evaluation (e.g., when referring to the symbol itself instead of its contents or to a list representing data instead of a function).

Lists are evaluated by first evaluating the first list element before the rest of the expression (as in Scheme). The result of the evaluation is applied to the remaining elements in the list and must be one of the following: a lambda expression, lambda-macro expression, or primitive (built-in) function.

For a user-defined lambda expression, newLISP evaluates the arguments from left to right and binds the results to the parameters (also from left to right), before using the results in the body of the expression.

Like Scheme, newLISP evaluates the functor (function object) part of an expression before applying the result to its arguments. For example:

Depending on the value of X, this expression applies the * (product) or + (sum) function to X and Y.

Because their arguments are not evaluated, lambda-macro expressions are useful for extending the syntax of the language. Most built-in functions evaluate their arguments from left to right (as needed) when executed. Some exceptions to this rule are indicated in the reference section of this manual. Lisp functions that do not evaluate all or some of their arguments are called special forms.

Shell commands: If an ! (exclamation mark) is entered as the first character on the command-line followed by a shell command, the command will be executed. For example, !ls on Unix or !dir on MS Windows will display a listing of the present working directory. No spaces are permitted between the ! and the shell command. Symbols beginning with an ! are still allowed inside expressions or on the command-line when preceded by a space. Note: This mode only works when running in the shell and does not work when controlling newLISP from another application.

To exit the newLISP shell on Linux/Unix, press Ctrl-D; on MS Windows, type (exit) or Ctrl-C, then the x key.

Use the exec function to access shell commands from other applications or to pass results back to newLISP.

9. Lambda expressions in newLISP

Lambda expressions in newLISP evaluate to themselves and can be treated just like regular lists:

Note: No ' is necessary before the lambda expression because lambda expressions evaluate to themselves in newLISP.

The second line uses the keyword fn, an alternative syntax first suggested by Paul Graham for his Arc language project.

A lambda expression is a lambda list, a subtype of list, and its arguments can associate from left to right or right to left. When using append, for example, the arguments associate from left to right:

Note that the lambda keyword is not a symbol in a list, but a designator of a special type of list: the lambda list.

Lambda expressions can be mapped or applied onto arguments to work as user-defined, anonymous functions:

A lambda expression can be assigned to a symbol, which in turn can be used as a function:

The define function is just a shorter way of assigning a lambda expression to a symbol:

In the above example, the expressions inside the lambda list are still accessible within double:

A lambda list can be manipulated as a first-class object using any function that operates on lists:

All arguments are optional when applying lambda expressions and default to nil when not supplied by the user. This makes it possible to write functions with multiple parameter signatures.

10. nil, true, cons, and ()

In newLISP, nil and true represent both the symbols and the Boolean values false and true. Depending on their context, nil and true are treated differently. The following examples use nil, but they can be applied to true by simply reversing the logic.

Evaluation of nil yields a Boolean false and is treated as such inside flow control expressions such as if, unless, while, until, and not. Likewise, evaluating true yields true.

In the above example, nil represents a symbol. In the following example, nil and true are evaluated and represent Boolean values:

In newLISP, nil and the empty list () are not the same as in some other Lisps. Only in conditional expressions are they treated as a Boolean false, as in and, or, if, while, unless, until, and cond.

Evaluation of (cons 'x '()) yields (x), but (cons 'x nil) yields (x nil) because nil is treated as a Boolean value when evaluated, not as an empty list. The cons of two atoms in newLISP does not yield a dotted pair, but rather a two-element list. The predicate atom? is true for nil, but false for the empty list. The empty list in newLISP is only an empty list and not equal to nil.

A list in newLISP is a newLISP cell of type list. It acts like a container for the linked list of elements making up the list cell's contents. There is no dotted pair in newLISP because the cdr (tail) part of a Lisp cell always points to another Lisp cell and never to a basic data type, such as a number or a symbol. Only the car (head) part may contain a basic data type. Early Lisp implementations used car and cdr for the names head and tail.

11. Arrays

newLISP's arrays enable fast element access within large lists. New arrays can be constructed and initialized with the contents of an existing list using the function array. Lists can be converted into arrays, and vice versa. Most of the same functions used for modifying and accessing lists can be applied to arrays, as well. Arrays can hold any type of data or combination thereof.

In particular, the following functions can be used for creating, accessing, and modifying arrays:

newLISP represents multidimensional arrays with an array of arrays (i.e., the elements of the array are themselves arrays).

When used interactively, newLISP prints and displays arrays as lists, with no way of distinguishing between them.

function	description
append	appends arrays
apply	apply a function or operator to a list of arguments.
array	creates and initializes an array with up to 16 dimensions
array-list	converts an array into a list
array?	checks if expression is an array
corr	calculates the product-moment correlation coefficient
det	returns the determinant of a matrix
dolist	evaluates once for each element in an array vector
first	returns the first row of an array
invert	returns the inversion of a matrix
last	returns the last row of an array
length	returns the number of rows in an array or elements in a vector
map	applies a function to vector(s) of arguments and returns results in a list.
mat	perform scalar operations on matrices
multiply	multiplies two matrices
nth	returns an element of and array
rest	returns all but the first row of an array
reverse	reverses the elements or rows in an array
setf	sets contents of an array reference
slice	returns a slice of an array
sort	sort the elements in an array
stats	calculates some basic statistics for a data vector
t-test	compares means of data samples using the Student's t statistic
transpose	transposes a matrix

Use the source or save functions to serialize arrays (or the variables containing them). The array statement is included as part of the definition when serializing arrays.

Like lists, negative indices can be used to enumerate the elements of an array, starting from the last element.

Arrays can be non-rectangular, but they are made rectangular during serialization when using source or save. The array function always constructs arrays in rectangular form.

The matrix functions det, transpose, multiply, and invert can be used on matrices built with nested lists or arrays built with array.

For more details, see array, array?, and array-list in the reference section of this manual.

12. Indexing elements of strings, lists, and arrays

Some functions take array, list, or string elements (characters) specified by one or more int-index (integer index). The positive indices run 0, 1, …, N-2, N-1, where N is the number of elements in the list. If int-index is negative, the sequence is -N, -N+1, …, -2, -1. Adding N to the negative index of an element yields the positive index. Unless a function does otherwise, an index greater than N-1 or less then -N causes an out-of-bounds error in lists and arrays.

Implicit indexing for nth

Implicit indexing can be used instead of nth to retrieve the elements of a list or array or the characters of a string:

Indices may also be supplied from a list. In this way, implicit indexing works together with functions that take or produce index vectors, such as push, pop, ref and ref-all.

Note that implicit indexing is not breaking newLISP syntax rules but is merely an expansion of existing rules to other data types in the functor position of an s-expression. In original Lisp, the first element in an s-expression list is applied as a function to the rest elements as arguments. In newLISP, a list in the functor position of an s-expression assumes self-indexing functionality using the index arguments following it.

Implicit indexing is faster than the explicit forms, but the explicit forms may be more readable depending on context.

Note that in the UTF-8–enabled version of newLISP, implicit indexing of strings or using the nth function work on character rather than single-byte boundaries.

Implicit indexing and the default functor

The default functor is a functor inside a context with the same name as the context itself. See The context default function chapter. A default functor can be used together with implicit indexing to serve as a mechanism for referencing lists:

In this example, aList references MyList:MyList, not a copy of it. For more information about contexts, see Variables holding contexts.

The indexed default functor can also be used with setf as shown in the following example:

Implicit indexing for rest and slice

Implicit forms of rest and slice can be created by prepending a list with one or two numbers for offset and length. If the length is negative it counts from the end of the list or string:

The functions rest, first and last work on multi-byte character boundaries in UTF-8 enabled versions of newLISP. But the implicit indexing forms for slicing and resting will always work on single-byte boundaries and can be used for binary content. Offset and length results from the regular expression functions find and regex are also in single-byte counts and can be further processed with slice or it's implicit form.

Modify references in lists, arrays and strings

Parts in lists, arrays and strings referenced by indices can be modified using setf:

Note that only full elements or nested lists or arrays can be changed this way. Slices or rest parts of lists or arrays as used in implicit resting or slicing cannot be substituted at once using setf, but would have to be substituted element by element. In strings only one character can be replaced at a time, but that character can be replaced by a multi-character string.

13. Destructive versus nondestructive functions

Most of the primitives in newLISP are nondestructive (no side effects) and leave existing objects untouched, although they may create new ones. There are a few destructive functions, however, that do change the contents of a variable, list, array, or string:

Make a destructive function non-destructive

function	description
++	increments numbers in integer mode
--	decrements numbers in integer mode
bind	binds variable associations in a list
constant	sets the contents of a variable and protects it
extend	extends a list or string
dec	decrements a number referenced by a variable, list or array
define	sets the contents of a variable
define-macro	sets the contents of a variable
inc	increments a number referenced by a variable, list or array
let	declares and initializes local variables
letn	initializes local variables incrementally, like nested lets
letex	expands local variables into an expression, then evaluates
net-receive	reads into a buffer variable
pop	pops an element from a list or string
pop-assoc	removes an association from an association list
push	pushes a new element onto a list or string
read	reads into a buffer variable
receive	receives a message from a parent or child process
replace	replaces elements in a list or string
reverse	reverses a list or string
rotate	rotates the elements of a list or characters of a string
set	sets the contents of a variable
setf setq	sets the contents of a variable, list, array or string
set-ref	searches for an element in a nested list and replaces it
set-ref-all	searches for an element in a nested list and replaces all instances
sort	sorts the elements of a list or array
swap	swaps two elements inside a list or string

Some destructive functions can be made non-destructive by wrapping the target object into the copy function.

14. Early return from functions, loops, and blocks

What follows are methods of interrupting the control flow inside both loops and the begin expression.

The looping functions dolist and dotimes can take optional conditional expressions to leave the loop early. catch and throw are a more general form to break out of a loop body and are also applicable to other forms or statement blocks.

Using catch and throw

Because newLISP is a functional language, it uses no break or return statements to exit functions or iterations. Instead, a block or function can be exited at any point using the functions catch and throw:

If condition-A is true, x will be returned from the catch expression; if condition-B is true, the value returned is y. Otherwise, the result from foo5 will be used as the return value.

As an alternative to catch, the error-event function can be used to catch errors caused by faulty code or user-initiated exceptions.

Using and and or

Using the logical functions and and or, blocks of statements can be built that are exited depending on the Boolean result of the enclosed functions:

The and expression will return as soon as one of the block's functions returns nil or an () (empty list). If none of the preceding functions causes an exit from the block, the result of the last function is returned.

The result of the or expression will be the first function that returns a value which is not nil or ().

15. Dynamic and lexical scoping

newLISP uses dynamic scoping inside contexts. A context is a lexically closed namespace. In this way, parts of a newLISP program can live in different namespaces taking advantage of lexical scoping.

When the parameter symbols of a lambda expression are bound to its arguments, the old bindings are pushed onto a stack. newLISP automatically restores the original variable bindings when leaving the lambda function.

The following example illustrates the dynamic scoping mechanism. The text in bold is the output from newLISP:

The variable x is first set to 1. But when (g 0) is called, x is bound to 0 and x is reported by (f) as 0 during execution of (g 0). After execution of (g 0), the call to (f) will report x as 1 again.

This is different from the lexical scoping mechanisms found in languages like C or Java, where the binding of local parameters occurs inside the function only. In lexically scoped languages like C, (f) would always print the global bindings of the symbol x with 1.

Be aware that passing quoted symbols to a user-defined function causes a name clash if the same variable name is used as a function parameter:

Because the global y shares the same symbol as the function's second parameter, inc-symbol returns 246 (123 + 123), leaving the global y unaffected. Dynamic scoping's variable capture can be a disadvantage when passing symbol references to user-defined functions. newLISP offers several methods to avoid variable capture.

Contexts should be used to group related functions when creating interfaces or function libraries. This surrounds the functions with a lexical "fence", thus avoiding variable name clashes with the calling functions.

newLISP uses contexts for different forms of lexical scoping. See the chapters Contexts and default functors for more information.

16. Contexts

In newLISP, symbols can be separated into namespaces called contexts. Each context has a private symbol table separate from all other contexts. Symbols known in one context are unknown in others, so the same name may be used in different contexts without conflict.

Contexts are used to build modules of isolated variable and function definitions. They also can be used to build dictionaries fo key values pairs. Contexts can be copied and dynamically assigned to variables or passed as arguments by reference. Because contexts in newLISP have lexically separated namespaces, they allow programming with lexical scoping and software object styles of programming.

Contexts are identified by symbols that are part of the root or MAIN context. Although context symbols are uppercased in this chapter, lowercase symbols may also be used.

In addition to context names, MAIN contains the symbols for built-in functions and special symbols such as true and nil. The MAIN context is created automatically each time newLISP is run. To see all the symbols in MAIN, enter the following expression after starting newLISP:

Symbol creation in contexts

The following rules should simplify the process of understanding contexts by identifying to which context the created symbols are being assigned.

Creating contexts

Contexts can be created either by using the context function or via implicit creation. The first method is used when writing larger portions of code belonging to the same context:

If the context does not exist yet, the context symbol must be quoted. If the symbol is not quoted, newLISP assumes the symbol is a variable holding the symbol of the context to create. Because a context evaluates to itself, already existing contexts like MAIN do not require quoting.

When newLISP reads the above code, it will read, then evaluate the first statement: (context 'FOO). This causes newLISP to switch the namespace to FOO and the following symbols var, x, y and z will all be created in the FOO context when reading and evaluating the remaining expressions.

A context symbol is protected against change. Once a symbol refers to a context, it cannot be used for any other purpose, except when using delete.

To refer to var or func from anywhere else outside the FOO namespace, they need to be prefixed with the context name:

Note, that in the above example only func belongs to the FOO name space the symbols p q r all are part of the current context from which the FOO:func call is made.

A context is implicitly created when referring to one that does not yet exist. Unlike the context function, the context is not switched. The following statements are all executed inside the MAIN context:

Note that only the symbols prefixed with their context name will be part of the context:

When above code is loaded in MAIN only foo will be part of ACTX. The symbols x and y will still be part of MAIN. To make all locals of ACTX:foo members of the ACTX context, they would either have to be prefixed with ACTX, or the whole funtion must be preceded by a context switch satement at the top level:

When loading source files on the command-line with load, or when executing the functions eval-string or sym, the context function tells the newLISP source code reader in which namespace to put all of the symbols and definitions:

The draw-triangle and draw-circle functions — along with their x, y, and z parameters — are now part of the GRAPH context. These symbols are known only to GRAPH. To call these functions from another context, prefix them with GRAPH:

The last statement shows how the runtime context has changed to GRAPH (function foo's context).

A symbol's name and context are used when comparing symbols from different contexts. The term function can be used to extract the term part from a fully qualified symbol.

Note: The symbols in above example are quoted with a ' (single quote) because we are interested in the symbol itself, not in the contents of the symbol.

Global scope

By default, only built-in functions and symbols like nil and true are visible inside contexts other than MAIN. To make a symbol visible to every context, use the global function:

Without the global statement, the second aVar would have returned nil instead of 123. If FOO had a previously defined symbol (aVar in this example) that symbol's value — and not the global's — would be returned instead. Note that only symbols from the MAIN context can be made global.

Once it is made visible to contexts through the global function, a symbol cannot be hidden from them again.

Symbol protection

By using the constant function, symbols can be both set and protected from change at the same time:

A symbol needing to be both a constant and a global can be defined simultaneously:

In the current context, symbols protected by constant can be overwritten by using the constant function again. This protects the symbols from being overwritten by code in other contexts.

Overwriting global symbols and built-ins

Global and built-in function symbols can be overwritten inside a context by prefixing them with their own context symbol:

In this example, the built-in function new is overwritten by Account:new, a different function that is private to the Account context.

Variables containing contexts

Context variables are useful when writing functions, which need to refer to different contexts during runtime or use contexts which do not exist during definition:

The following shows a terminal session using above definitions. The program output is shown in bold-face:

The same one function update can display different behavior depending on the context passed as first parameter.

Sequence of creating or loading contexts

The sequence in which contexts are created or loaded can lead to unexpected results. Enter the following code into a file called demo:

Loading the file causes an error message for FOO, but not for ABC. When the first context FOO is loaded, the context ABC does not exist yet, so a local variable FOO:ABC gets created. When ABC loads, FOO already exists as a global protected symbol and will be correctly flagged as protected.

FOO could still be used as a local variable in the ABC context by explicitly prefixing it, as in ABC:FOO.

Contexts as programming modules

Contexts in newLISP are mainly used for partitioning source into modules. Because each module lives in a different namespace, modules are lexically separated and the names of symbols cannot clash with identical names in other modules.

The modules, which are part of the newLISP distribution, are a good example of how to put related functions into a module file, and how to document modules using the newLISPdoc utility.

For best programming practice, a file should only contain one module and the filename should be similar if not identical to the context name used:

The example shows a good practice of predefining variables, which are global inside the namespace, and defining as constants the variables that will not change.

If a file must contain more than one context, then the end of the context should be marked with a switch back to MAIN:

In any case load will always switch back to the context from where it was called.

Contexts as data containers

Loading the Config namespace will now load a whole variable set into memory at once:

Loading and declaring contexts

Module files are loaded using the load function. If a programming project contains numerous modules that refer to each other, they can be pre-declared to avoid problems due to context forward references that can occur before the loading of that context.

When pre-declaring and loading modules as shown in the example, the sequence of declaration or loading can be neglected. All forward references to variables and definitions in modules not loaded yet will be translated correctly. Wrong usage of a context symbol will result in an error message before that context is loaded.

Modules not starting with a context switch are always loaded into MAIN except when the load statement specifies a target context as the last parameter. The load function can take URLs to load modules from remote locations, via HTTP.

The current context after the load statement will always be the same as before the load.

Serializing contexts

Serialization makes a software object persistent by converting it into a character stream, which is then saved to a file or string in memory. In newLISP, anything referenced by a symbol can be serialized to a file by using the save function. Like other symbols, contexts are saved just by using their names:

For details, see the functions save (mentioned above) and source (for serializing to a newLISP string).

17. The context default functor

A default functor or default function is a symbol or user-defined function or macro with the same name as its namespace. When the context is used as the name of a function or in the functor position of an s-expression, newLISP executes the default function.

If a default function is called from a context other than MAIN, the context must already exist or be declared with a forward declaration, which creates the context and the function symbol:

Default functions work like global functions, but they are lexically separate from the context in which they are called.

Like a lambda or lambda-macro function, default functions can be used with map or apply.

Functions with memory

A default function can update the lexically isolated static variables contained inside its namespace:

The first time the Gen function is called, its accumulator is set to the value of the argument. Each successive call increments Gen's accumulator by the argument's value.

The definition of Gen:Gen shows, how a function is put in its own namespace without using the surrounding (context 'Gen) and (context MAIN) statements. In that case only symbols qualified by the namespace prefix will end up in the Gen context. In the above example the variable x is still part of MAIN.

Hash functions and dictionaries

There are several functions that can be used to place symbols into namespace contexts. When using dictionaries as simple hash-like collections of variable → value pairs, use the uninitialized default functor:

Either method can be used to make the MyHash dictionary space and default functor. The second method is safer, as it will protect the default functor MyHash:MyHash from change. The default functor in a namespace must contain nil to be used as a dictionary. Creating key-value pairs and retrieving a value is easy:

Symbol variables created this way can contain spaces or other characters normally not allowed in newLISP symbol names:

Like many built-in functions hash expressions return a reference to their content which can be modified directly:

When setting hash values the anaphoric system variable $it can be used to refer to the old value when setting the new:

But supplying the value as a second parameter to the hash functions is shorter to write and faster.

Internally the key strings are created and stored as symbols in the hash context. All key strings are prepended with an _ underscore character. This protects against overwriting the default symbol and symbols like set and sym, which are needed when loading a hash namespace from disk or over HTTP. Note the following difference:

In the first line hash symbols are shown as strings without the preceding underscore characters. The second line shows the internal form of the symbols with prepended underscore characters.

Passing data by reference

A default functor can also be used to hold data. If this data contains a list or string, the context name can be used as a reference to the data:

Most of the time, newLISP passes parameters by value copy. This poses a potential problem when passing large lists or strings to user-defined functions or macros. Strings and lists, which are packed in a namespace using default functors, are passed automatically by reference:

Any argument of a built-in function calling for either a list or a string — but no other data type — can receive data passed by reference. Any user-defined function can take either normal variables, or can take a context name for passing a reference to the default functor containing a list or string.

Note that on lists with less than about 100 elements or strings of less than about 50000 characters, the speed difference between reference and value passing is negligible. But on bigger data objects, differences in both speed and memory usage between reference and value passing can be significant.

Built-in and user-defined functions are suitable for both types of arguments, but when passing context names, data will be passed by reference.

Quoted symbols can also be used to pass data by reference, but this method has disadvantages:

Although this method is simple to understand and use, it poses the potential problem of variable capture when passing the same symbol as used as a function parameter:

At the beginning of the chapter it was shown how to package data in a name-space using a default functor. Not only the default functor but any symbol in context can be used to hold data. The disadvantage is that the calling function must have knowledge about the symbol being used:

The function receives the namespace in the variable obj, but it must have the knowledge that the list to access is contained in the data symbol of that namespace (context).

18. Functional object-oriented programming

Functional-object oriented programming (FOOP) is based on the following five principles:

The following paragraphs are a short introduction to FOOP as designed by Michael Michaels from neglook.com.

FOOP classes and constructors

Class attributes and methods are stored in the namespace of the object class. No object instance data is stored in this namespace/context. Data variables in the class namespace only describe the class of objects as a whole but don't contain any object specific information. A generic FOOP object constructor can be used as a template for specific object constructors when creating new object classes with new:

The generic FOOP constructor is already pre-defined, and FOOP code can start with (new Class ...) statements right away.

As a matter of style, new classes should only be created in the MAIN context. If creating a new class while in a different namespace, the new class name must be prefixed with MAIN and the statement should be on the top-level:

Creating the namespace classes using new reserves the class name as a context in newLISP and facilitates forward references. At the same time, a simple constructor is defined for the new class for instantiating new objects. As a convention, it is recommended to start class names in upper-case to signal that the name stands for a namespace.

In some cases, it may be useful to overwrite the simple constructor, that was created during class creation, with new:

In many cases the constructor as created when using new is sufficient and overwriting it is not necessary.

Objects and associations

FOOP represents objects as lists. The first element of the list indicates the object's kind or class, while the remaining elements contain the data. The following statements define two objects using any of the constructors defined previously:

An object created is identical to the function necessary to create it (hence FOOP). Nested objects can be created in a similar manner:

Objects in FOOP not only resemble functions they also resemble associations. The assoc function can be used to access object data by name:

Note that in none of the assoc statements Address and Street need to carry quotes. The same is true in the set statement: (set 'JohnDoe (Person ...)) for the data part assigned. In both cases we do not deal with symbols or lists of symbols but rather with contexts and FOOP objects which evaluate to themselves. Quoting would not make a difference.

The colon : operator and polymorphism

In newLISP, the colon character : is primarily used to connect the context symbol with the symbol it is qualifying. Secondly, the colon function is used in FOOP to resolve a function's application polymorphously.

The following code defines two functions called area, each belonging to a different namespace / class. Both functions could have been defined in different modules for better separation, but in this case they are defined in the same file and without bracketing context statements. Here, only the symbols rectangle:area and circle:area belong to different namespaces. The local parameters p, c, dx, and dy are all part of MAIN, but this is of no concern.

By prefixing the area or move symbol with the : (colon), we can call these functions for each class of object. Although there is no space between the colon and the symbol following it, newLISP parses them as distinct entities. The colon works as a function that processes parameters:

In this example, the correct qualified symbol (rectangle:area or circle:area) is constructed and applied to the object data based on the symbol following the colon and the context name (the first element of the object list).

Note, that although the caller specifies the called target object of the call, the method definition does not include the object as a parameter. When writing functions to modify FOOP objects, instead the function self is used to access and index the object.

Structuring a larger FOOP program

In all the previous examples, class function methods where directly written into the MAIN context namespace. This works and is adequate for smaller programs written by just one programmer. When writing larger systems, all the methods for one class should be surrounded by context statements to provide better isolation of parameter variables used and to create an isolated location for potential class variables.

Class variables could be used in this example as a container for lists of objects, counters or other information specific to a class but not to a specific object. The following code segment rewrites the example from above in this fashion.

Each context / namespace could go into an extra file with the same name as the class contained. Class creation, startup code and the main control code is in a file MAIN.lsp:

19. Concurrent processing and distributed computing

newLISP has high-level APIs to control multiple processes on the same CPU or distributed onto different computer nodes on a TCP/IP network.

Cilk API

newLISP implements a Cilk- like API to launch and control concurrent processes. The API can take advantage of multi-core computer architectures. Only three functions, spawn, sync and abort, are necessary to start multiple processes and collect the results in a synchronized fashion. The underlying operating system distributes processes onto different cores inside the CPU or executes them on the same core in parallel if there are not enough cores present. Note that newLISP only implements the API; optimized scheduling of spawned procedures is not performed as in Cilk. Functions are started in the order they appear in spawn statements and are distributed and scheduled onto different cores in the CPU by the operating system.

When multiple cores are present, this can increase overall processing speed by evaluating functions in parallel. But even when running on single core CPUs, the Cilk API makes concurrent processing much easier for the programmer and may speed up processing if subtasks include waiting for I/O or sleeping.

Since version 10.1 send and receive message functions are available for communications between parent and child processes. The functions can be used in blocking and non blocking communications and can transfer any kind of newLISP data or expressions. Transmitted expressions can be evaluated in the recipients environment.

Internally, newLISP uses the lower level fork, wait-pid, destroy, and share functionalities to control processes and synchronize the passing of computed results via a shared memory interface.

Only on Mac OS X and other Unixes will the Cilk API parallelize tasks. On MS Windows, the API partly simulates the behavior on Unix but executes tasks sequentially. This way, code can be written that runs on all platforms.

Distributed network computing

With only one function, net-eval, newLISP implements distributed computing. Using net-eval, different tasks can be mapped and evaluated on different nodes running on a TCP/IP network or local domain Unix sockets network when running on the same computer. net-eval does all the housekeeping required to connect to remote nodes, transfer functions to execute, and collect the results. net-eval can also use a call-back function to further structure consolidation of incoming results from remote nodes.

The functions read-file, write-file, append-file and delete-file all can take URLs instead of path-file names. Server side newLISP running in demon mode or an other HTTP server like Apache, receive standard HTTP requests and translate them into the corresponding actions on files.

20. JSON, XML, S-XML, and XML-RPC

JSON-encoded data can be parsed into S-expressions using the json-parse function. Error information for failed JSON translations can be retrieved using json-error.

For a description of the JSON format (JavaScript Object Notation) consult json.org. Examples for correct formatted JSON text can be seen at json.org/examples.html.

To retrieve data in nested lists resulting from JSON translation, use the assoc, lookup and ref functions.

See the description of json-parse for a complete example of parsing and processing JSON data.

newLISP's built-in support for XML-encoded data or documents comprises three functions: xml-parse, xml-type-tags, and xml-error.

Use the xml-parse function to parse XML-encoded strings. When xml-parse encounters an error, nil is returned. To diagnose syntax errors caused by incorrectly formatted XML, use the function xml-error. The xml-type-tags function can be used to control or suppress the appearance of XML type tags. These tags classify XML into one of four categories: text, raw string data, comments, and element data.

S-XML can be generated directly from XML using xml-type-tags and the special option parameters of the xml-parse function:

S-XML is XML reformatted as newLISP S-expressions. The @ (at symbol) denotes an XML attribute specification.

To retrieve data in nested lists resulting from S-XML translation, use the assoc, lookup and ref functions.

See xml-parse in the reference section of the manual for details on parsing and option numbers, as well as for a longer example.

The remote procedure calling protocol XML-RPC uses HTTP post requests as a transport and XML for the encoding of method names, parameters, and parameter types. XML-RPC client libraries and servers have been implemented for most popular compiled and scripting languages.

XML-RPC clients and servers are easy to write using newLISP's built-in network and XML support. A stateless XML-RPC server implemented as a CGI service can be found in the file examples/xmlrpc.cgi. This script can be used together with a web server, like Apache. This XML-RPC service script implements the following methods:

method	description
`system.listMethods`	Returns a list of all method names
`system.methodHelp`	Returns help for a specific method
`system.methodSignature`	Returns a list of return/calling signatures for a specific method
`newLISP.evalString`	Evaluates a Base64 newLISP expression string

The first three methods are discovery methods implemented by most XML-RPC servers. The last one is specific to the newLISP XML-RPC server script and implements remote evaluation of a Base64-encoded string of newLISP source code. newLISP's base64-enc and base64-dec functions can be used to encode and decode Base64-encoded information.

In the modules directory of the source distribution, the file xmlrpc-client.lsp implements a specific client interface for all of the above methods.

All functions return either a result if successful, or nil if a request fails. In case of failure, the expression (XMLRPC:error) can be evaluated to return an error message.

For more information, please consult the header of the file modules/xmlrpc-client.lsp.

21. Customization, localization, and UTF-8

Customizing function names

The constant function, rather than the set function, must be used to rename built-in primitive symbols. By default, all built-in function symbols are protected against accidental overwriting.

It is possible to redefine all integer arithmetic operators to their floating point equivalents:

All operations using +, -, *, and / are now performed as floating point operations.

Using the same mechanism, the names of built-in functions can be translated into languages other than English:

Switching the locale

newLISP can switch locales based on the platform and operating system. On startup, non-UTF-8 enabled newLISP attempts to set the ISO C standard default POSIX locale, available for most platforms and locales. On UTF-8 enabled newLISP the default locale for the platform is set. The set-locale function can also be used to switch to the default locale:

This switches to the default locale used on your platform/operating system and ensures character handling (e.g., upper-case) works correctly.

Many Unix systems have a variety of locales available. To find out which ones are available on a particular Linux/Unix/BSD system, execute the following command in a system shell:

This command prints a list of all the locales available on your system. Any of these may be used as arguments to set-locale:

This would switch to a U.S. Spanish locale. Accents or other characters used in a U.S. Spanish environment would be correctly converted.

Decimal point and decimal comma

Many countries use a comma instead of a period as a decimal separator in numbers. newLISP correctly parses numbers depending on the locale set:

The default POSIX C locale, which is set when newLISP starts up, uses a period as a decimal separator.

Unicode and UTF-8 encoding

Note that for many European languages, the set-locale mechanism is sufficient to display non-ASCII character sets, as long as each character is presented as one byte internally. UTF-8 encoding is only necessary for multi-byte character sets as described in this chapter.

newLISP can be compiled as a UTF-8–enabled application. UTF-8 is a multi-byte encoding of the international Unicode character set. A UTF-8–enabled newLISP running on an operating system with UTF-8 enabled can handle any character of the installed locale.

The following steps make UTF-8 work with newLISP on a specific operating system and platform:

(1) Use one of the makefiles ending in utf8 to compile newLISP as a UTF-8 application. If no UTF-8 makefile is available for your platform, the normal makefile for your operating system contains instructions on how to change it for UTF-8.

(2) Enable the UTF-8 locale on your operating system. Check and set a UTF-8 locale on Unix and Unix-like OSes by using the locale command or the set-locale function within newLISP. On Linux, the locale can be changed by setting the appropriate environment variable. The following example uses bash to set the U.S. locale:

(3) The UTF-8–enabled newLISP automatically switches to the locale found on the operating system. Make sure the command shell is UTF-8–enabled. The U.S. version of WinXP's notepad.exe can display Unicode UTF-8–encoded characters, but the command shell cannot. On Linux and other Unixes, the Xterm shell can be used when started as follows:

The following procedure can now be used to check for UTF-8 support. After starting newLISP, type:

While the uppercase omega (Ω) looks like a big O on two tiny legs, the lowercase omega (ω) has a shape similar to a small w in the Latin alphabet.

Note: Only the output of println will be displayed as a character; println's return value will appear on the console as a multi-byte ASCII character.

When UTF-8–enabled newLISP is used on a non-UTF-8–enabled display, both the output and the return value will be two characters. These are the two bytes necessary to encode the omega character.

Functions working on UTF-8 characters

When UTF-8–enabled newLISP is used, the following string functions work on one- or multi-byte characters rather than one 8-bit byte boundaries:

function	description
char	translates between characters and ASCII/Unicode
chop	chops characters from the end of a string
date	converts date number to string (when used with the third argument)
dostring	evaluates once for each character in a string
explode	transforms a string into a list of characters
first	gets first element in a list (car, head) or string
last	returns the last element of a list or string
lower-case	converts a string to lowercase characters
nth	gets the nth element of a list or string
pop	deletes an element from a list or string
push	inserts a new element in a list or string
rest	gets all but the first element of a list (cdr, tail) or string
select	selects and permutes elements from a list or string
title-case	converts the first character of a string to uppercase
trim	trims a string from both sides
upper-case	converts a string to uppercase characters

All other string functions work on 8-bit bytes. When positions are returned, as in find or regex, they are single 8-bit byte positions rather than character positions which may be multi-byte. The get-char and slice functions do not take multi-byte character offsets, but single-byte offsets, even in UTF-8 enabled versions of newLISP. The reverse function reverses a byte vector, not a character vector. The last three functions can still be used to manipulate binary non-textual data in the UTF-8–enabled version of newLISP. To make slice and reverse work with UTF-8 strings, combine them with explode and join.

To enable UTF-8 in Perl Compatible Regular Expressions (PCRE) — used by directory, find, member, parse, regex, regex-comp and replace — set the option number accordingly (2048). Note that offset and lengths in regex results are always in single byte counts. See the regex documentation for details.

Use explode to obtain an array of UTF-8 characters and to manipulate characters rather than bytes when a UTF-8–enabled function is unavailable:

The above string functions (often used to manipulate non-textual binary data) now work on character, rather than byte, boundaries, so care must be exercised when using the UTF-8–enabled version. The size of the first 127 ASCII characters — along with the characters in popular code pages such as ISO 8859 — is one byte long. When working exclusively within these code pages, UTF-8–enabled newLISP is not required. The set-locale function alone is sufficient for localized behavior.

Functions only available on UTF-8 enabled versions

function	description
unicode	converts UTF-8 or ASCII strings into USC-4 Unicode
utf8	converts UCS-4 Unicode strings to UTF-8
utf8len	returns the number of UTF-8 characters in a string

The first two functions are rarely used in practice, as most Unicode text files are already UTF-8–encoded (rather than UCS-4, which uses four-byte integer characters). Unicode can be displayed directly when using the "%ls" format specifier.

22. Commas in parameter lists

Some of the example programs contain functions that use a comma to separate the parameters into two groups. This is not a special syntax of newLISP, but rather a visual trick. The comma is a symbol just like any other symbol. The parameters after the comma are not required when calling the function; they simply declare local variables in a convenient way. This is possible in newLISP because parameter variables in lambda expressions are local and arguments are optional:

When calling this function, only a, b, and c are used as parameters. The others (the comma symbol, x, y, and z) are initialized to nil and are local to the function. After execution, the function's contents are forgotten and the environment's symbols are restored to their previous values.

For other ways of declaring and initializing local variables, see let, letex and letn.

1. Syntax of symbol variables and numbers

Source code in newLISP is parsed according to the rules outlined here. When in doubt, verify the behavior of newLISP's internal parser by calling parse without optional arguments.

Symbols for variable names

The following rules apply to the naming of symbols used as variables or functions:

Sometimes it is useful to create hash-like lookup dictionaries with keys containing characters that are illegal in newLISP variables. The functions sym and context can be used to create symbols containing these characters:

The last example creates the symbol 1 containing the value 123. Also note that creating such a symbol does not alter newLISP's normal operations, since 1 is still parsed as the number one.

Numbers

When parsing binary, hex, decimal, float and integer numbers, up to 1000 digits are parsed when present. The rest will be read as new token(s). Note that IEEE 754 64-bit doubles distinguish only up to 16 significant digits. If more than 308 digits are present before the decimal point, the number will convert to inf (infinity). For big integers the 1000 limitation exists only when parsing source. There is no limit when a result of big integers math exceeds 1000 digits.

Integers are one or more digits long, optionally preceded by a + or - sign. Any other character marks the end of the integer or may be part of the sequence if parsed as a float (see float syntax below).

Big integers can be of unlimited precision and are processed differently from normal 64-bi integers internally.

when parsing the command line or programming source, newLISP will recognise, integers bigger than 64-bit and convert the to big integers. Smaller numbers can be forced to big integer format by appending the letter L.

Hexadecimals start with a 0x (or 0X), followed by any combination of the hexadecimal digits: 0123456789abcdefABCDEF. Any other character ends the hexadecimal number. Only up to 16 hexadecimal digits are valid and any more digits are ignored.

Binaries start with a 0b (or 0B), followed by up to 64 bits coded with 1's or 0s. Any other character ends the binary number. Only up to 64 bits are valid and any more bits are ignored.

Octals start with an optional + (plus) or - (minus) sign and a 0 (zero), followed by any combination of the octal digits: 01234567. Any other character ends the octal number. Only up to 21 octal digits are valid and any more digits are ignored.

Floating point numbers can start with an optional + (plus) or - (minus) sign, but they cannot be followed by a 0 (zero); this would make them octal numbers instead of floating points. A single . (decimal point) can appear anywhere within a floating point number, including at the beginning.

As described below, scientific notation starts with a floating point number called the significand (or mantissa), followed by the letter e or E and an integer exponent.

2. Data types and names in the reference

To describe the types and names of a function's parameters, the following naming convention is used throughout the reference section:

Arguments are represented by symbols formed by the argument's type and name, separated by a - (hyphen). Here, str-format (a string) and exp-data-1 (an expression) are named "format" and "data-1", respectively.

Arguments enclosed in brackets [ and ] are optional. When arguments are separated by a vertical | then one of them must be chosen.

array

body

One or more expressions for evaluation. The expressions are evaluated sequentially if there is more than one.

bool

context

An expression evaluating to a context (namespace) or a variable symbol holding a context.

exp

func

A symbol or an expression evaluating to an operator symbol or lambda expression.

int

An integer or an expression evaluating to an integer. Generally, if a floating point number is used when an int is expected, the value is truncated to an integer.

list

num

An integer, a floating point number, or an expression evaluating to one of these two. If an integer is passed, it is converted to a floating point number.

matrix

A list in which each row element is itself a list or an array in which each row element is itself an array. All element lists or arrays (rows) are of the same length. Any data type can be element of a matrix, but when using specific matrix operations like det, multiply, or invert, all numbers must be floats or integers.

The dimensions of a matrix are defined by indicating the number of rows and the number of column elements per row. Functions working on matrices ignore superfluous columns in a row. For missing row elements, 0.0 is assumed by the functions det, multiply, and invert, while transpose assumes nil. Special rules apply for transpose when a whole row is not a list or an array, but some other data type.

place

A place referenced by a symbol or a place defined in a list, array or string by indexing with nth or implicit indexing or a place referenced by functions like first, last, assoc or lookup.

str

Depending on the length and processing of special characters, strings are delimited by either quotes "", braces {} or [text][/text] tags.

Strings limited by either quotes "" or braces {} must not exceed 2047 characters. Longer strings should be limited by [text][/text] tags for unlimited text length.

Special characters can be included in quoted strings by placing a \ (backslash) before the character or digits to escape them:

character	description
`\"`	for a double quote inside a quoted string
`\n`	the line-feed character (ASCII 10)
`\r`	the carriage return character (ASCII 13)
`\b`	for a backspace BS character (ASCII 8)
`\t`	for a TAB character (ASCII 9)
`\f`	for a formfeed FF character (ASCII 12)
`\nnn`	a decimal ASCII code where nnn is between 000 and 255
`\xnn`	a hexadecimal code where nn is between 00 and FF
`\unnnn`	a unicode character encoded in the four `nnnn` hexadecimal digits. When reading a quoted string, newLISP will translate this to a UTF8 character in the UTF8 enabled versions of newLISP.
`\\`	the backslash character itself

Instead of a " (double quote), a { (left curly bracket) and } (right curly bracket) can be used to delimit strings. This is useful when quotation marks need to occur inside strings. Quoting with the curly brackets suppresses the backslash escape effect for special characters. Balanced nested curly brackets may be used within a string. This aids in writing regular expressions or short sections of HTML.

The tags [text] and [/text] can be used to delimit long strings and suppress escape character translation. This is useful for delimiting long HTML passages in CGI files written in newLISP or for situations where character translation should be completely suppressed. Always use the [text] tags for strings longer than 2048 characters.

sym

Most of the context symbols in this manual start with an uppercase letter to distinguish them from other symbols.

sym-context

A symbol, an existing context, or an expression evaluating to a symbol from which a context will be created. If a context does not already exist, many functions implicitly create them (e.g., bayes-train, context, eval-string, load, sym, and xml-parse). The context must be specified when these functions are used on an existing context. Even if a context already exists, some functions may continue to take quoted symbols (e.g., context). For other functions, such as context?, the distinction is critical.

3. Functions in groups

List processing, flow control, and integer arithmetic

String and conversion functions

Floating point math and special functions

Matrix functions

Array functions

Bit operators

Predicates

Date and time functions

Statistics, simulation and modeling functions

Pattern matching

Financial math functions

Input/output and file operations

Processes and the Cilk API

File and directory management

HTTP networking API

Socket TCP/IP, UDP and ICMP network API

API for newLISP in a web browser

Reflection and customization

System functions

Importing libraries

newLISP internals API

4. Functions in alphabetical order

syntax: (! str-shell-command [int-flags])

Executes the command in str-command by shelling out to the operating system and executing. This function returns a different value depending on the host operating system.

Use the exec function to execute a shell command and capture the standard output or to feed standard input. The process function may be used to launch a non-blocking child process and redirect std I/O and std error to pipes.

On Ms Windows the optional int-flags parameter takes process creation flags as defined for the Windows CreateProcessA function to control various parameters of process creation. The inclusion of this parameter – which also can be 0 – forces a different creation of the process without a command shell window. This parameter is ignored on Unix.

Without the additional parameter, the ! call would create a new command window replacing the closed one.

Note that ! (exclamation mark) can be also be used as a command-line shell operator by omitting the parenthesis and space after the !:

Used in this way, the ! operator is not a newLISP function at all, but rather a special feature of the newLISP command shell. The ! must be entered as the first character on the command-line.

syntax: ($ int-idx)

The functions that use regular expressions (directory, ends-with, find, find-all, parse, regex, search, starts-with and replace) all bind their results to the predefined system variables $0, $1, $2–$15 after or during the function's execution. System variables can be treated the same as any other symbol. As an alternative, the contents of these variables may also be accessed by using ($ 0), ($ 1), ($ 2), etc. This method allows indexed access (i.e., ($ i), where i is an integer).

+, -, *, / ,% bigint

syntax: (+ int-1 [int-2 ... ])

syntax: (- int-1 [int-2 ... ])

Subtracts int-2 from int-1, then the next int-i from the previous result. If only one argument is given, its sign is reversed.

syntax: (* int-1 [int-2 ... ])

syntax: (/ int-1 [int-2 ... ])

Each result is divided successively until the end of the list is reached. Division by zero causes an error.

syntax: (% int-1 [int-2 ... ])

Each result is divided successively by the next int, then the rest (modulo operation) is returned. Division by zero causes an error. For floating point numbers, use the mod function.

Floating point values in arguments to +, -, *, /, and % are truncated to the integer value closest to 0 (zero).

Floating point values larger or smaller than the maximum (9,223,372,036,854,775,807) or minimum (-9,223,372,036,854,775,808) integer values are truncated to those values. This includes the values for +Inf and -Inf.

Calculations resulting in values larger than 9,223,372,036,854,775,807 or smaller than -9,223,372,036,854,775,808 wrap around from positive to negative or negative to positive.

Floating point values that evaluate to NaN (Not a Number), ar treated as 0 (zero).

++ ! bigint

syntax: (++ place [num ... ])

The ++ operator works like inc, but performs integer arithmetic. Without the optional argument in num, ++ increments the number in place by 1.

If floating point numbers are passed as arguments, their fractional part gets truncated first.

Calculations resulting in numbers greater than 9,223,372,036,854,775,807 wrap around to negative numbers. Results smaller than -9,223,372,036,854,775,808 wrap around to positive numbers.

place is either a symbol or a place in a list structure holding a number, or a number returned by an expression.

See -- for decrementing numbers in integer mode. See inc for incrementing numbers in floating point mode.

-- ! bigint

syntax: (-- place [num ... ])

The -- operator works like dec, but performs integer arithmetic. Without the optional argument in num-2, -- decrements the number in place by 1.

If floating point numbers are passed as arguments, their fractional part gets truncated first.

Calculations resulting in numbers greater than 9,223,372,036,854,775,807 wrap around to negative numbers. Results smaller than -9,223,372,036,854,775,808 wrap around to positive numbers.

place is either a symbol or a place in a list structure holding a number, or a number returned by an expression.

See ++ for incrementing numbers in integer mode. See dec for decrementing numbers in floating point mode.

<, >, =, <=, >=, != bigint

syntax: (< exp-1 [exp-2 ... ])
syntax: (> exp-1 [exp-2 ... ])
syntax: (= exp-1 [exp-2 ... ])
syntax: (<= exp-1 [exp-2 ... ])
syntax: (>= exp-1 [exp-2 ... ])
syntax: (!= exp-1 [exp-2 ... ])

Expressions are evaluated and the results are compared successively. As long as the comparisons conform to the comparison operators, evaluation and comparison will continue until all arguments are tested and the result is true. As soon as one comparison fails, nil is returned.

If only one argument is supplied, all comparison operators assume 0 (zero) as a second argument. This can be used to check if a number is negative, positive, zero or not zero.

All types of expressions can be compared: atoms, numbers, symbols, and strings. List expressions can also be compared (list elements are compared recursively).

When comparing lists, elements at the beginning of the list are considered more significant than the elements following (similar to characters in a string). When comparing lists of different lengths but equal elements, the longer list is considered greater (see examples).

In mixed-type expressions, the types are compared from lowest to highest. Floats and integers are compared by first converting them to the needed type, then comparing them as numbers.

<<, >>

syntax: (<< int-1 int-2 [int-3 ... ])
syntax: (>> int-1 int-2 [int-3 ... ])
syntax: (<< int-1)
syntax: (>> int-1)

The number int-1 is arithmetically shifted to the left or right by the number of bits given as int-2, then shifted by int-3 and so on. For example, 64-bit integers may be shifted up to 63 positions. When shifting right, the most significant bit is duplicated (arithmetic shift):

syntax: (& int-1 int-2 [int-3 ... ])

A bitwise and operation is performed on the number in int-1 with the number in int-2, then successively with int-3, etc.

syntax: (| int-1 int-2 [int-3 ... ])

A bitwise or operation is performed on the number in int-1 with the number in int-2, then successively with int-3, etc.

syntax: (^ int-1 int-2 [int-3 ... ])

A bitwise xor operation is performed on the number in int-1 with the number in int-2, then successively with int-3, etc.

syntax: (~ int)

A bitwise not operation is performed on the number in int, reversing all of the bits.

syntax: (: sym-function list-object [ ... ])

The colon is used not only as a syntactic separator between namespace prefix and the term inside but also as an operator. When used as an operator, the colon : constructs a context symbol from the context name in the object list and the symbol following the colon. The object list in list-object can be followed by other parameters.

The : operator implements polymorphism of object methods, which are part of different object classes represented by contexts (namespaces). In newLISP, an object is represented by a list, the first element of which is the symbol (name) of its class context. The class context implements the functions applicable to the object. No space is required between the colon and the symbol following it.

Inside the FOOP methods the self function is used to access the target object of the method.

abort

syntax: (abort int-pid)
syntax: (abort)

In the first form, abort aborts a specific child process of the current parent process giving the process id in int-pid. The process must have been started using spawn. For processes started using fork, use destroy instead.

To abort all child processes spawned from the current process use abort without any parameters:

The function abort is part of the Cilk API for synchronizing child processes and process parallelization. See the reference for the function spawn for a full discussion of the Cilk API.

abs bigint

syntax: (abs num)

acos

syntax: (acos num-radians)

acosh

syntax: (acosh num-radians)

Calculates the inverse hyperbolic cosine of num-radians, the value whose hyperbolic cosine is num-radians. If num-radians is less than 1, acosh returns NaN.

add

syntax: (add num-1 [num-2 ... ])

All of the numbers in num-1, num-2, and on are summed. add accepts float or integer operands, but it always returns a floating point number. Any floating point calculation with NaN also returns NaN.

address

syntax: (address int)
syntax: (address float)
syntax: (address str)

Returns the memory address of the integer in int, the double floating point number in float, or the string in str. This function is used for passing parameters to library functions that have been imported using the import function.

When a string is passed to C library function the address of the string is used automatically, and it is not necessary to use the address function in that case. As the example shows, address can be used to do pointer arithmetic on the string's address.

address should only be used on persistent addresses from data objects referred to by a variable symbol, not from volatile intermediate expression objects.

amb

syntax: (amb exp-1 [exp-2 ... ])

One of the expressions exp-1 ... n is selected at random, and the evaluation result is returned.

Internally, newLISP uses the same function as rand to pick a random number. To generate random floating point numbers, use random, randomize, or normal. To initialize the pseudo random number generating process at a specific starting point, use the seed function.

and

syntax: (and exp-1 [exp-2 ... ])

The expressions exp-1, exp-2, etc. are evaluated in order, returning the result of the last expression. If any of the expressions yield nil or the empty list (), evaluation is terminated and nil or the empty list () is returned.

append

syntax: (append list-1 [list-2 ... ])
syntax: (append array-1 [array-2 ... ])
syntax: (append str-1 [str-2 ... ])

In the first form, append works with lists, appending list-1 through list-n to form a new list. The original lists are left unchanged.

In the third form, append works on strings. The strings in str-n are concatenated into a new string and returned.

append is also suitable for processing binary strings containing zeroes. The string function would cut off strings at zero bytes.

Linkage characters or strings can be specified using the join function. Use the string function to convert arguments to strings and append in one step.

Use the functions extend and push to append to an existing list or string modifying the target.

append-file

syntax: (append-file str-filename str-buffer)

Works similarly to write-file, but the content in str-buffer is appended if the file in str-filename exists. If the file does not exist, it is created (in this case, append-file works identically to write-file). This function returns the number of bytes written.

On failure the function returns nil. For error information, use sys-error when used on files. When used on URLs net-error gives more error information.

append-file can take a http:// or file:// URL in str-file-name. In case of the http:// prefix , append-file works exactly like put-url with "Pragma: append\r\n" in the header option and can take the same additional parameters. The "Pragma: append\r\n" option is supplied automatically.

The file message.txt is appended at a remote location http://asite.com with the contents of str-buffer. If the file does not yet exist, it will be created. In this mode, append-file can also be used to transfer files to remote newLISP server nodes.

apply

syntax: (apply func list [int-reduce])
syntax: (apply func)

Applies the contents of func (primitive, user-defined function, or lambda expression) to the arguments in list. Only functions and operators with standard evaluation of their arguments can be applied.

The int-reduce parameter can optionally contain the number of arguments taken by the function in func. In this case, func will be repeatedly applied using the previous result as the first argument and taking the other arguments required successively from list (in left-associative order). For example, if op takes two arguments, then:

The last example shows how apply's reduce functionality can be used to convert a two-argument function into one that takes multiple arguments. Note, that a built-in gcd is available.

apply should only be used on functions and operators that evaluate all of their arguments, not on special forms like dotimes or case, which evaluate only some of their arguments. Doing so will cause the function to fail.

args

syntax: (args)
syntax: (args int-idx-1 [int-idx-2 ... ])

Accesses a list of all unbound arguments passed to the currently evaluating define, define-macro lambda, or lambda-macro expression. Only the arguments of the current function or macro that remain after local variable binding has occurred are available. The args function is useful for defining functions or macros with a variable number of parameters.

args can be used to define hygienic macros that avoid the danger of variable capture. See define-macro.

This example prints a line-feed after each argument. The macro mimics the effect of the built-in function println.

The function foo prints out the arguments in reverse order. The bar function shows args being used with multiple indices to access nested lists.

Remember that (args) only contains the arguments not already bound to local variables of the current function or macro:

In the first example, an empty list is returned because the arguments are bound to the two local symbols, a and b. The second example demonstrates that, after the first two arguments are bound (as in the first example), three arguments remain and are then returned by args.

(args) can be used as an argument to a built-in or user-defined function call, but it should not be used as an argument to another macro, in which case (args) would not be evaluated and would therefore have the wrong contents in the new macro environment.

array

syntax: (array int-n1 [int-n2 ... ] [list-init])

Creates an array with int-n1 elements, optionally initializing it with the contents of list-init. Up to sixteen dimensions may be specified for multidimensional arrays.

Internally, newLISP builds multidimensional arrays by using arrays as the elements of an array. newLISP arrays should be used whenever random indexing into a large list becomes too slow. Not all list functions may be used on arrays. For a more detailed discussion, see the chapter on arrays.

Arrays can be initialized with objects of any type. If fewer initializers than elements are provided, the list is repeated until all elements of the array are initialized.

Arrays are modified and accessed using most of the same functions used for modifying lists:

When serializing arrays using the function source or save, the generated code includes the array statement necessary to create them. This way, variables containing arrays are correctly serialized when saving with save or creating source strings using source.

array-list

syntax: (array-list array)

array?

syntax: (array? exp)

asin

syntax: (asin num-radians)

Calculates the arcsine function from the number in num-radians and returns the result.

asinh

syntax: (asinh num-radians)

Calculates the inverse hyperbolic sine of num-radians, the value whose hyperbolic sine is num-radians.

assoc

syntax: (assoc exp-key list-alist)
syntax: (assoc list-exp-key list-alist)

In the first syntax the value of exp-key is used to search list-alist for a member-list whose first element matches the key value. If found, the member-list is returned; otherwise, the result will be nil.

In the second syntax more then one key expressions can be specified to search in nested, multilevel association lists:

The list in list-aList can be a context which will be interpreted as its default functor. This way very big lists can be passed by reference for speedier access and less memory usage:

For making replacements in association lists, use the setf together with the assoc function. The lookup function is used to perform association lookup and element extraction in one step.

atan

syntax: (atan num-radians)

atan2

syntax: (atan2 num-Y-radians num-X-radians)

The atan2 function computes the principal value of the arctangent of Y / X in radians. It uses the signs of both arguments to determine the quadrant of the return value. atan2 is useful for converting Cartesian coordinates into polar coordinates.

atanh

syntax: (atanh num-radians)

Calculates the inverse hyperbolic tangent of num-radians, the value whose hyperbolic tangent is num-radians. If the absolute value of num-radians is greater than 1, atanh returns NaN; if it is equal to 1, atanh returns infinity.

atom?

syntax: (atom? exp)

Returns true if the value of exp is an atom, otherwise nil. An expression is an atom if it evaluates to nil, true, an integer, a float, a string, a symbol or a primitive. Lists, lambda or lambda-macro expressions, and quoted expressions are not atoms.

base64-dec

syntax: (base64-dec str)

The BASE64 string in str is decoded. Note that str is not verified to be a valid BASE64 string. The decoded string is returned.

newLISP's BASE64 handling is derived from routines found in the Unix curl utility and conforms to the RFC 4648 standard.

base64-enc

syntax: (base64-enc str [bool-flag])

The string in str is encoded into BASE64 format. This format encodes groups of 3 * 8 = 24 input bits into 4 * 8 = 32 output bits, where each 8-bit output group represents 6 bits from the input string. The 6 bits are encoded into 64 possibilities from the letters A–Z and a–z; the numbers 0–9; and the characters + (plus sign) and / (slash). The = (equals sign) is used as a filler in unused 3- to 4-byte translations. This function is helpful for converting binary content into printable characters.

Without the optional bool-flag parameter the empty string "" is encoded into "====". If bool-flag evaluates to true, the empty string "" is translated into "". Both translations result in "" when using base64-dec.

BASE64 encoding is used with many Internet protocols to encode binary data for inclusion in text-based messages (e.g., XML-RPC).

Note that base64-enc does not insert carriage-return/line-feed pairs in longer BASE64 sequences but instead returns a pure BASE64-encoded string.

newLISP's BASE64 handling is derived from routines found in the Unix curl utility and conforms to the RFC 4648 standard.

bayes-query

syntax: (bayes-query list-L context-D [bool-chain [bool-probs]])

Takes a list of tokens (list-L) and a trained dictionary (context-D) and returns a list of the combined probabilities of the tokens in one category (A or Mc) versus a category (B) or against all other categories (Mi). All tokens in list-L should occur in context-D. When using the default R.A. Fisher inverse Chi² mode, nonexistent tokens will skew results toward equal probability in all categories.

Non-existing tokens will not have any influence on the result when using the true Chain Bayesian mode with bool-chain set to true. The optional last flag, bool-probs, indicates whether frequencies or probability values are used in the data set. The bayes-train function is typically used to generate a data set's frequencies.

Tokens can be strings or symbols. If strings are used, they are prepended with an underscore before being looked up in context-D. If bayes-train was used to generate context-D's frequencies, the underscore was automatically prepended during the learning process.

Depending on the flag specified in bool-probs, bayes-query employs either the R. A. Fisher inverse Chi² method of compounding probabilities or the Chain Bayesian method. By default, when no flag or nil is specified in bool-probs, the inverse Chi² method of compounding probabilities is used. When specifying true in bool-probs, the Chain Bayesian method is used.

If the inverse Chi² method is used, the total number of tokens in the different training set's categories should be equal or similar. Uneven frequencies in categories will skew the results.

The probabilities (p(Mi) or p(A), along with p(B)) represent the Bayesian prior probabilities. p(Mc|tkn) and p(A|tkn) are the posterior Bayesian probabilities of a category or model. This naive Bayes formula does nor take into account dependencies between different categories.

Priors are handled differently, depending on whether the R.A. Fisher inverse Chi² or the Chain Bayesian method is used. In Chain Bayesian mode, posteriors from one token calculation get the priors in the next calculation. In the default inverse Chi² method, priors are not passed on via chaining, but probabilities are compounded using the inverse Chi² method.

In Chain Bayes mode, tokens with zero frequency in one category will effectively put the probability of that category to 0 (zero). This also causes all posterior priors to be set to 0 and the category to be completely suppressed in the result. Queries resulting in zero probabilities for all categories yield NaN values.

The default inverse Chi² method is less sensitive about zero frequencies and still maintains a low probability for that token. This may be an important feature in natural language processing when using Bayesian statistics. Imagine that five different language corpus categories have been trained, but some words occurring in one category are not present in another. When the pure Chain Bayesian method is used, a sentence could never be classified into its correct category because the zero-count of just one word token could effectively exclude it from the category to which it belongs.

On the other hand, the Chain Bayesian method offers exact results for specific proportions in the data. When using Chain Bayesian mode for natural language data, all zero frequencies should be removed from the trained dictionary first.

The return value of bayes-query is a list of probability values, one for each category. Following are two examples: the first for the default inverse Chi² mode, the second for a data set processed with the Chain Bayesian method.

R.A. Fisher inverse Chi² method

In the following example, the two data sets are books from Project Gutenberg. We assume that different authors use certain words with different frequencies and want to determine if a sentence is more likely to occur in one or the other author's writing. A similar method is frequently used to differentiate between spam and legitimate email.

The two training sets are loaded, split into tokens, and processed by the bayes-train function. In the end, the DoyleDowson dictionary is saved to a file, which will be used later with the bayes-query function.

The following code illustrates how bayes-query is used to classify a sentence as Doyle or Dowson:

The queries correctly identify the first sentence as a Dowson sentence, and the second one as a Doyle sentence.

Chain Bayesian method

The second example is frequently found in introductory literature on Bayesian statistics. It shows the Chain Bayesian method of using bayes-query on the data of a previously processed data set:

A disease occurs in 10 percent of the population. A blood test developed to detect this disease produces a false positive rate of 20 percent in the healthy population and a false negative rate of 20 percent in the sick. What is the probability of a person carrying the disease after testing positive?

Note that the Bayesian formulas used assume statistical independence of events for the bayes-query to work correctly.

The example shows that a person must test positive several times before they can be confidently classified as sick.

Calculating the same example using the R.A. Fisher Chi² method will give less-distinguished results.

Specifying probabilities instead of counts

Often, data is already available as probability values and would require additional work to reverse them into frequencies. In the last example, the data were originally defined as percentages. The additional optional bool-probs flag allows probabilities to be entered directly and should be used together with the Chain Bayesian mode for maximum performance:

As expected, the results are the same for probabilities as they are for frequencies.

bayes-train

syntax: (bayes-train list-M1 [list-M2 ... ] sym-context-D)

Takes one or more lists of tokens (M1, M2—) from a joint set of tokens. In newLISP, tokens can be symbols or strings (other data types are ignored). Tokens are placed in a common dictionary in sym-context-D, and the frequency is counted for each token in each category Mi. If the context does not yet exist, it must be quoted.

The M categories represent data models for which sequences of tokens can be classified (see bayes-query). Each token in D is a content-addressable symbol containing a list of the frequencies for this token within each category. String tokens are prepended with an _ (underscore) before being converted into symbols. A symbol named total is created containing the total of each category. The total symbol cannot be part of the symbols passed as an Mi category.

The function returns a list of token frequencies found in the different categories or models.

The first example shows training with two lists of symbols. The second example illustrates how an _ is prepended when training with strings.

bayes-train creates symbols from strings prepending an underscore character. This is the same way hashes are created and contexts populates with symbols by bayes-train can be used like hashes:

Note that these examples are just for demonstration purposes. In reality, training sets may contain thousands or millions of words, especially when training natural language models. But small data sets may be used when the frequency of symbols just describe already-known proportions. In this case, it may be better to describe the model data set explicitly, without the bayes-train function:

The last data are from a popular example used to describe the bayes-query function in introductory papers and books about bayesian networks.

Training can be done in different stages by using bayes-train on an existing trained context with the same number of categories. The new symbols will be added, then counts and totals will be correctly updated.

Training in multiple batches may be necessary on big text corpora or documents that must be tokenized first. These corpora can be tokenized in small portions, then fed into bayes-train in multiple stages. Categories can also be singularly trained by specifying an empty list for the absent corpus:

Using bayes-train inside a context other than MAIN requires the training contexts to have been created previously within the MAIN context via the context function.

bayes-train is not only useful with the bayes-query function, but also as a function for counting in general. For instance, the resulting frequencies could be analyzed using prob-chi2 against a null hypothesis of proportional distribution of items across categories.

begin

syntax: (begin body)

The begin function is used to group a block of expressions. The expressions in body are evaluated in sequence, and the value of the last expression in body is returned.

The silent function works like begin, but suppresses console output on return.

beta

syntax: (beta cum-a num-b)

The Beta function, beta, is derived from the log Gamma gammaln function as follows:

betai

syntax: (betai num-x num-a num-b)

The Incomplete Beta function, betai, equals the cumulative probability of the Beta distribution, betai, at x in num-x. The cumulative binomial distribution is defined as the probability of an event, pev, with probability p to occur k or more times in N trials:

The example calculates the probability for an event with a probability of 0.5 to occur 3 or more times in 10 trials (8 = 10 - 3 + 1). The incomplete Beta distribution can be used to derive a variety of other functions in mathematics and statistics. See also the binomial function.

bigint

syntax: (bigint number)
syntax: (bigint string)

A floating point or integer number gets converted to big integer format. When converting from floating point, rounding errors occur going back and forth between decimal and binary arithmetic.

bigint?

syntax: (bigint? number)

bind !

syntax: (bind list-variable-associations [bool-eval])

list-variable-associations contains an association list of symbols and their values. bind sets all symbols to their associated values.

binomial

syntax: (binomial int-n int-k float-p)

The binomial distribution function is defined as the probability for an event to occur int-k times in int-n trials if that event has a probability of float-p and all trials are independent of one another:

The example calculates the probability for an event with a probability of 0.5 to occur 3 times in 10 trials. For a cumulated distribution, see the betai function.

bits

syntax: (bits int [bool])

Transforms a number in int to a string of 1's and 0's or a list, if bool evaluates to anything not nil.

In string representation bits are in high to low order. In list presentation 1's and 0's are represented as true and nil and in order from the lowest to the highest bit. This allows direct indexing and program control switching on the result.

callback

syntax: (callback int-index sym-function)
syntax: (callback sym-function str-return-type [str_param_type ...])
syntax: (callback sym-function)

In the first simple callback syntax up to sixteen (0 to 15) callback functions for up to eight parameters can be registered with imported libraries. The callback function returns a procedure address that invokes a user-defined function in sym-function. The following example shows the usage of callback functions when importing the OpenGL graphics library:

If more than sixteen callback functions are required, slots must be reassigned to a different callback function.

The address returned by callback is registered with the Glut library. The above code is a snippet from the file opengl-demo.lsp, in the examples/ directory of the source distribution of newLISP and can also be downloaded from newlisp.org/downloads/OpenGL.

In the second extended callback syntax type specifiers are used to describe the functions return and parameter value types when the function is called. An unlimited number of callback functions can be registered with the second syntax, and return values are passed back to the calling function. The symbol in sym-function contains a newLISP defined function used as a callback function callable from a C program.

In the third syntax callback returns a previously returned C-callable address for that symbol.

While the first simple callback syntax only handles integers and pointer values, callback in the expanded syntax can also handle simple and double precision floating point numbers passed in an out of the callback function.

The following example shows the import of the qsort C library function, which takes as one of it's arguments the address of a comparison function. The comparison function in this case is written in newLISP and called into by the imported qsort function:

As type specifiers the same string tags can be used as in the import function. All pointer types are passed as numbers in and out of the callback function. The functions get-char, get-int, get-long and get-string can be used to extract numbers of different precision from parameters. Use pack and unpack to extract data from binary buffers and structures.

case

syntax: (case exp-switch (exp-1 body-1) [(exp-2 body-2) ... ])

The result of evaluating exp-switch is compared to each of the unevaluated expressions exp-1, exp-2, —. If a match is found, the corresponding expressions in body are evaluated. The result of the last body expression is returned as the result for the entire case expression.

The example shows how, if no match is found, the last expression in the body of a case function can be evaluated.

catch

syntax: (catch exp)
syntax: (catch exp symbol)

In the first syntax, catch will return the result of the evaluation of exp or the evaluated argument of a throw executed during the evaluation of exp:

This form is useful for breaking out of iteration loops and for forcing an early return from a function or expression block:

In the second syntax, catch evaluates the expression exp, stores the result in symbol, and returns true. If an error occurs during evaluation, catch returns nil and stores the error message in symbol. This form can be useful when errors are expected as a normal potential outcome of a function and are dealt with during program execution.

When a throw is executed during the evaluation of exp, catch will return true, and the throw argument will be stored in symbol:

As well as being used for early returns from functions and for breaking out of iteration loops (as in the first syntax), the second syntax of catch can also be used to catch errors. The throw-error function may be used to throw user-defined errors.

ceil

syntax: (ceil number)

change-dir

syntax: (change-dir str-path)

Changes the current directory to be the one given in str-path. If successful, true is returned; otherwise nil is returned.

char utf8

syntax: (char str [int-index [true]])
syntax: (char int)

Given a string argument, extracts the character at int-index from str, returning either the ASCII value of that character or the Unicode value on UTF-8 enabled versions of newLISP.

If int-index is omitted, 0 (zero) is assumed. If int-idx is followed by a boolean true value, than the index treats str as an 8-bit byte array instead of an array of multi-byte UTF-8 characters.

The empty string returns nil. Both (char 0) and (char nil) will return "\000".

Given an integer argument, char returns a string containing the ASCII character with value int.

On UTF-8–enabled versions of newLISP, the value in int is taken as Unicode and a UTF-8 character is returned.

chop utf8

syntax: (chop str [int-chars])
syntax: (chop list [int-elements])

If the first argument evaluates to a string, chop returns a copy of str with the last int-char characters omitted. If the int-char argument is absent, one character is omitted. chop does not alter str.

If the first argument evaluates to a list, a copy of list is returned with int-elements omitted (same as for strings).

clean

syntax: (clean exp-predicate list)

The predicate exp-predicate is applied to each element of list. In the returned list, all elements for which exp-predicate is true are eliminated.

The predicate may be a built-in predicate or a user-defined function or lambda expression.

For cleaning numbers from one list using numbers from another, use difference or intersect (with the list mode option).

See also the related function index, which returns the indices of the remaining elements, and filter, which returns all elements for which a predicate returns true.

syntax: (close int-file)

Closes the file specified by the file handle in int-file. The handle would have been obtained from a previous open operation. If successful, close returns true; otherwise nil is returned.

Note that using close on device automatically resets it to 0 (zero, the screen device).

collect

syntax: (collect exp [int-max-count])

Evaluates the expression in exp and collects the results in a list until evaluation of exp returns nil.

command-event

syntax: (command-event sym-event-handler | func-event-handler)
syntax: (command-event nil)

Specifies a user defined function for pre-processing the newLISP command-line before it gets evaluated. This can be used to write customized interactive newLISP shells and to transform HTTP requests when running in server mode.

command-event takes either a symbol of a user-defined function or a lambda function. The event-handler function must return a string or the command-line will be passed untranslated to newLISP.

To only force a prompt and disable command processing, the function should return the empty string "". To reset command-event, use the second syntax.

The following example makes the newLISP shell work like a normal Unix shell when the command starts with a letter. But starting the line with an open parenthesis or a space initiates a newLISP evaluation.

See also the related prompt-event which can be used for further customizing interactive mode by modifying the newLISP prompt.

The following program can be used either stand-alone or included in newLISP's init.lsp startup file:

In the definition of the command-line translation function the Unix command cd gets a special treatment, to make sure that the directory is changed for newLISP process too. This way when shelling out with ! and coming back, newLISP will maintain the changed directory.

Command lines for newLISP must start either with a space or an opening parenthesis. Unix commands must start at the beginning of the line.

When newLISP is running in server mode either using the -c or -http option, it receives HTTP requests similar to the following:

A function specified by command-event could filter and transform these request lines, e.g.: discovering all queries trying to perform CGI using a file ending in .exe. Such a request would be translated into a request for an error page:

When starting the server mode with newlisp httpd-conf.lsp -c -d80 -w ./httpdoc newLISP will load the definition for command-event for filtering incoming requests, and the query:

The example shows a technique frequently used in the past by spammers on MS Windows based, bad configured web servers to gain control over servers.

httpd-conf.lsp files can easily be debugged loading the file into an interactive newLISP session and entering the HTTP requests manually. newLISP will translate the command line and dispatch it to the built-in web server. The server output will appear in the shell window.

Note, that the command line length as well as the line length in HTTP headers is limited to 512 characters for newLISP.

cond

syntax: (cond (exp-condition-1 body-1) [(exp-condition-2 body-2) ... ])

Like if, cond conditionally evaluates the expressions within its body. The exp-conditions are evaluated in turn, until some exp-condition-i is found that evaluates to anything other than nil or an empty list (). The result of evaluating body-i is then returned as the result of the entire cond-expression. If all conditions evaluate to nil or an empty list, cond returns the value of the last cond-expression.

When a body-n is missing, the value of the last cond-expression evaluated is returned. If no condition evaluates to true, the value of the last conditional expression is returned (i.e., nil or an empty list).

When used with multiple arguments, the function if behaves like cond, except it does not need extra parentheses to enclose the condition-body pair of expressions.

cons

syntax: (cons exp-1 exp-2)

If exp-2 evaluates to a list, then a list is returned with the result of evaluating exp-1 inserted as the first element. If exp-2 evaluates to anything other than a list, the results of evaluating exp-1 and exp-2 are returned in a list. Note that there is no dotted pair in newLISP: consing two atoms constructs a list, not a dotted pair.

Unlike other Lisps that return (s) as the result of the expression (cons 's nil), newLISP's cons returns (s nil). In newLISP, nil is a Boolean value and is not equivalent to an empty list, and a newLISP cell holds only one value.

cons behaves like the inverse operation of first and rest (or first and last if the list is a pair):

constant !

syntax: (constant sym-1 exp-1 [sym-2 exp-2] ...)

Identical to set in functionality, constant further protects the symbols from subsequent modification. A symbol set with constant can only be modified using the constant function again. When an attempt is made to modify the contents of a symbol protected with constant, newLISP generates an error message. Only symbols from the current context can be used with constant. This prevents the overwriting of symbols that have been protected in their home context. The last exp-n initializer is always optional.

Symbols initialized with set, define, or define-macro can still be protected by using the constant function:

The first example defines a constant, aVar, which can only be changed by using another constant statement. The second example protects double from being changed (except by constant). Because a function definition in newLISP is equivalent to an assignment of a lambda function, both steps can be collapsed into one, as shown in the last statement line. This could be an important technique for avoiding protection errors when a file is loaded multiple times.

The last value to be assigned can be omitted. constant returns the contents of the last symbol set and protected.

Built-in functions can be assigned to symbols or to the names of other built-in functions, effectively redefining them as different functions. There is no performance loss when renaming functions.

squareroot will behave like sqrt. The + (plus sign) is redefined to use the mixed type floating point mode of add. The hexadecimal number displayed in the result is the binary address of the built-in function and varies on different platforms and OSes.

context

syntax: (context [sym-context])
syntax: (context sym-context str | sym [exp-value])

In the first syntax, context is used to switch to a different context namespace. Subsequent loads of newLISP source or functions like eval-string and sym will put newly created symbols and function definitions in the new context.

If the context still needs to be created, the symbol for the new context should be specified. When no argument is passed to context, then the symbol for the current context is returned.

Because contexts evaluate to themselves, a quote is not necessary to switch to a different context if that context already exists.

If a context symbol is referred to before the context exists, the context will be created implicitly.

If an identifier with the same symbol already exists, it is redefined to be a context.

Symbols within the current context are referred to simply by their names, as are built-in functions and special symbols like nil and true. Symbols outside the current context are referenced by prefixing the symbol name with the context name and a : (colon). To quote a symbol in a different context, prefix the context name with a ' (single quote).

Within a given context, symbols may be created with the same name as built-in functions or context symbols in MAIN. This overwrites the symbols in MAIN when they are prefixed with a context:

In the second syntax, context can be used to create symbols in a namespace. Note that this should not be used for creating hashes or dictionaries. For a shorter, more convenient method to use namespaces as hash-like dictionaries, see the chapter Hash functions and dictionaries.

The first three statements create a symbol and store a value of any data type inside. The first statement also creates the context named Ctx. When a symbol is specified for the name, the name is taken from the symbol and creates a symbol with the same name in the context Ctx.

Symbols can contain spaces or any other special characters not typically allowed in newLISP symbols being used as variable names. This second syntax of context only creates the new symbol and returns the value contained in it. It does not switch to the new namespace.

context?

syntax: (context? exp)
syntax: (context? exp str-sym)

In the first syntax, context? is a predicate that returns true only if exp evaluates to a context; otherwise, it returns nil.

The second syntax checks for the existence of a symbol in a context. The symbol is specified by its name string in str-sym.

Use context to change and create namespaces and to create hash symbols in contexts.

copy

syntax: (copy exp)
syntax: (copy int-addr [bool-flag])

The first syntax makes a copy from evaluating expression in exp. Some built-in functions are destructive, changing the original contents of a list, array or string they are working on. With copy their behavior can be made non-destructive.

Using copy the functions replace and rotate are prevented from changing the data. A modified version of the data is returned.

The second syntax, marked by the true in bool-flag, copies a newLISP expression from a memory address.The following two expressions are equivalent:

The second syntax can be useful when interfacing with C-code generating newLISP expressions.

copy-file

syntax: (copy-file str-from-name str-to-name)

Copies a file from a path-filename given in str-from-name to a path-filename given in str-to-name. Returns true if the copy was successful or nil, if the copy was unsuccessful.

corr

syntax: (corr list-vector-X list-vector-Y)

Calculates the Pearson product-moment correlation coefficient as a measure of the linear relationship between the two variables in list-vector-X and list-vector-Y. Both lists must be of same length.

name	description
r	Correlation coefficient
b0	Regression coefficient offset
b1	Regression coefficient slope
t	t - statistic for significance testing
df	Degrees of freedom for t
p	Two tailed probability of t under the null hypothesis

The negative correlation of -0.926 between study time and test errors is highly significant with a two-tailed p of about 0.0001 under the null hypothesis.

The regression coefficients b0 = 29.241 and b1 = -0.064 can be used to estimate values of the Y variable (test errors) from values in X (study time) using the equation Y = b0 + b1 * X.

cos

syntax: (cos num-radians)

cosh

syntax: (cosh num-radians)

Calculates the hyperbolic cosine of num-radians. The hyperbolic cosine is defined mathematically as: (exp (x) + exp (-x)) / 2. An overflow to inf may occur if num-radians is too large.

count

syntax: (count list-1 list-2)

The first list in count, which specifies the items to be counted in the second list, should be unique. For items that are not unique, only the first instance will carry a count; all other instances will display 0 (zero).

cpymem ⚠

syntax: (cpymem int-from-address int-to-address int-bytes)

Copies int-bytes of memory from int-from-address to int-to-address. This function can be used for direct memory writing/reading or for hacking newLISP internals (e.g., type bits in newLISP cells, or building functions with binary executable code on the fly).

Note that this function should only be used when familiar with newLISP internals. cpymem can crash the system or make it unstable if used incorrectly.

The following example creates a new function from scratch, runs a piece of binary code, and adds up two numbers. This assembly language snippet shows the x86 (Intel CPU) code to add up two numbers and return the result:

Use the dump function to retrieve binary addresses and the contents from newLISP cells.

crc32

syntax: (crc32 str-data)

Calculates a running 32-bit CRC (Circular Redundancy Check) sum from the buffer in str-data, starting with a CRC of 0xffffffff for the first byte. crc32 uses an algorithm published by www.w3.org.

crit-chi2

syntax: (crit-chi2 num-probability int-df)

Calculates the critical minimum Chi² for a given confidence probability num-probability under the null hypothesis and the degrees of freedom in int-df for testing the significance of a statistical null hypothesis.

Note that versions prior to 10.2.0 took (1.0 - p) for the probability instead of p.

crit-f

syntax: (crit-f num-probability int-df1 int-df2)

Calculates the critical minimum F for a given confidence probability num-probability under the null hypothesis and the degrees of freedom given in int-df1 and int-df2 for testing the significance of a statistical null hypothesis using the F-test.

crit-t

syntax: (crit-t num-probability int-df)

Calculates the critical minimum Student's t for a given confidence probability num-probability under the null hypothesis and the degrees of freedom in int-df for testing the significance of a statistical null hypothesis.

crit-z

syntax: (crit-z num-probability)

Calculates the critical normal distributed Z value of a given cumulated probability num-probability for testing of statistical significance and confidence intervals.

current-line

syntax: (current-line)

Retrieves the contents of the last read-line operation. current-line's contents are also implicitly used when write-line is called without a string parameter.

The following source shows the typical code pattern for creating a Unix command-line filter:

This displays all comment lines starting with ;; from a file given as a command-line argument when invoking the script filter.

curry

syntax: (curry func exp)

Transforms func from a function f(x, y) that takes two arguments into a function fx(y) that takes a single argument. curry works like a macro in that it does not evaluate its arguments. Instead, they are evaluated during the application of func.

date utf8

syntax: (date)
syntax: (date int-secs [int-offset])
syntax: (date int-secs int-offset str-format)

The first syntax returns the local time zone's current date and time as a string representation. If int-secs is out of range, nil is returned.

In the second syntax, date translates the number of seconds in int-secs into its date/time string representation for the local time zone. The number in int-secs is usually retrieved from the system using date-value. Optionally, a time-zone offset (in minutes) can be specified in int-offset, which is added or subtracted before conversion of int-sec to a string. If int-secs is out of range or an invalid str-format is specified, an empty string "" is returned.

The way the date and time are presented in a string depends on the underlying operating system.

The second example would show 1-1-1970 0:0 when in the Greenwich time zone, but it displays a time lag of 8 hours when in Pacific Standard Time (PST). date assumes the int-secs given are in Coordinated Universal Time (UTC; formerly Greenwich Mean Time (GMT)) and converts it according to the local time-zone.

The third syntax makes the date string fully customizable by using a format specified in str-format. This allows the day and month names to be translated into results appropriate for the current locale:

The following table summarizes all format specifiers available on both MS Windows and Linux/Unix platforms. More format options are available on Linux/Unix. For details, consult the manual page for the C function strftime() of the individual platform's C library.

format	description
%a	abbreviated weekday name according to the current locale
%A	full weekday name according to the current locale
%b	abbreviated month name according to the current locale
%B	full month name according to the current locale
%c	preferred date and time representation for the current locale
%d	day of the month as a decimal number (range 01–31)
%H	hour as a decimal number using a 24-hour clock (range 00–23)
%I	hour as a decimal number using a 12-hour clock (range 01–12)
%j	day of the year as a decimal number (range 001–366)
%m	month as a decimal number (range 01–12)
%M	minute as a decimal number
%p	either 'am' or 'pm' according to the given time value or the corresponding strings for the current locale
%S	second as a decimal number 0–61 (60 and 61 to account for occasional leap seconds)
%U	week number of the current year as a decimal number, starting with the first Sunday as the first day of the first week
%w	day of the week as a decimal, Sunday being 0
%W	week number of the current year as a decimal number, starting with the first Monday as the first day of the first week
%x	preferred date representation for the current locale without the time
%X	preferred time representation for the current locale without the date
%y	year as a decimal number without a century (range 00–99)
%Y	year as a decimal number including the century
%z	time zone or name or abbreviation (same as %Z on MS Windows, different on Unix)
%Z	time zone or name or abbreviation (same as %z on MS Windows, different on Unix)
%%	a literal '%' character

Leading zeroes in the display of decimal day numbers can be suppressed using "%-d" on Linux and FreeBSD and using "%e" on OpenBSD, SunOS/Solaris and Mac OS X. On MS Windows use "%#d".

date-list

syntax: (date-list int-seconds [int-index])
syntax: (date-list)

Returns a list of year, month, date, hours, minutes, seconds, day of year and day of week from a time value given in seconds after January 1st, 1970 00:00:00. The date and time values aren given as UTC, which may differ from the local timezone.

When no parameters are given date-list generates the list from the number of seconds for the current time, return of (date-value).

A second optional int-index parameter can be used to return a specific member of the list.

date-parse

syntax: (date-parse str-date str-format)

Parses a date from a text string in str-date using a format as defined in str-format, which uses the same formatting rules found in date. The function date-parse returns the number of UTC seconds passed since January 1st, 1970 UTC starting with 0 and up to 2147472000 for a date of January 19th, 2038.

This function is not available on MS Windows platforms. The function was named parse-date in previous versions. The old form is deprecated.

date-value

syntax: (date-value int-year int-month int-day [int-hour int-min int-sec])
syntax: (date-value list-date-time)
syntax: (date-value)

In the first syntax, date-value returns the time in seconds since 1970-1-1 00:00:00 for a given date and time. The parameters for the hour, minutes and seconds are optional. The time is assumed to be Coordinated Universal Time (UTC), not adjusted for the current time zone.

In the second syntax the same data can be given in a list. As with the first syntax, numbers for the hour, minutes and seconds are optional.

In the third syntax, date-value returns the time value in seconds for the current time.

The function date-list can be used to transform a date-value back into a list:

debug

syntax: (debug func)

Calls trace and begins evaluating the user-defined function in func. debug is a shortcut for executing (trace true), then entering the function to be debugged.

When in debug or trace mode, error messages will be printed. The function causing the exception will return either 0 or nil and processing will continue. This way, variables and the current state of the program can still be inspected while debugging.

dec !

syntax: (dec place [num])

The number in place is decremented by 1.0 or the optional number num and returned. dec performs float arithmetic and converts integer numbers passed into floating point type.

place is either a symbol or a place in a list structure holding a number, or a number returned by an expression.

Places in a list structure or a number returned by another expression can be updated too:

Use the -- function to decrement in integer mode. Use the inc function to increment numbers floating point mode.

def-new

syntax: (def-new sym-source [sym-target])

This function works similarly to new, but it only creates a copy of one symbol and its contents from the symbol in sym-source. When sym-target is not given, a symbol with the same name is created in the current context. All symbols referenced inside sym-source will be translated into symbol references into the current context, which must not be MAIN.

If an argument is present in sym-target, the copy will be made into a symbol and context as referenced by the symbol in sym-target. In addition to allowing renaming of the function while copying, this also enables the copy to be placed in a different context. All symbol references in sym-source with the same context as sym-source will be translated into symbol references of the target context.

The following example shows how a statically scoped function can be created by moving it its own namespace:

The following definition of def-static can be used to create functions living in their own lexically protected name-space:

The function def-new can also be used to configure contexts or context objects in a more granular fashion than is possible with new, which copies a whole context.

default

syntax: (default context)

In many situations newLISP defaults automatically to the default functor when seeing a context name. In circumstances where this is not the case, the default function can be used.

define !

syntax: (define (sym-name [sym-param-1 ... ]) [body-1 ... ])
syntax: (define (sym-name [(sym-param-1 exp-default) ... ]) [body-1 ... ])
syntax: (define sym-name exp)

Defines the new function sym-name, with optional parameters sym-param-1—. define is equivalent to assigning a lambda expression to sym-name. When calling a defined function, all arguments are evaluated and assigned to the variables in sym-param-1—, then the body-1— expressions are evaluated. When a function is defined, the lambda expression bound to sym-name is returned.

All parameters defined are optional. When a user-defined function is called without arguments, those parameters assume the value nil. If those parameters have a default value specified in exp-default, they assume that value.

The return value of define is the assigned lambda expression. When calling a user-defined function, the return value is the last expression evaluated in the function body.

As an alternative, area could be defined as a function without using define.

lambda or fn expressions may be used by themselves as anonymous functions without being defined as a symbol:

Expressions in exp-default are evaluated in the function's current environment.

define-macro

syntax: (define-macro (sym-name [sym-param-1 ... ]) body)
syntax: (define-macro (sym-name [(sym-param-1 exp-default) ... ]) body)

Functions defined using define-macro are called fexpr in other LISPs as they don't do variable expansion. In newLISP they are still called macros, because they are written with the same purpose of creating special syntax forms with non-standard evaluation patterns of arguments. Functions created using define-macro can be combined with template expansion using expand or letex.

Defines the new fexpr sym-name, with optional arguments sym-param-1. define-macro is equivalent to assigning a lambda-macro expression to a symbol. When a define-macro function is called, unevaluated arguments are assigned to the variables in sym-param-1 .... Then the body expressions are evaluated. When evaluating the define-macro function, the lambda-macro expression is returned.

New functions can be created to behave like built-in functions that delay the evaluation of certain arguments. Because fexprs can access the arguments inside a parameter list, they can be used to create flow-control functions like those already built-in to newLISP.

All parameters defined are optional. When a macro is called without arguments, those parameters assume the value nil. If those parameters have a default value specified in exp-default, they assume that default value.

Expressions in exp-default are evaluated in the function's current environment.

Note that in fexprs, the danger exists of passing a parameter with the same variable name as used in the define-macro definition. In this case, the fexpr's internal variable would end up receiving nil instead of the intended value:

There are several methods that can be used to avoid this problem, known as variable capture, by writing hygienic define-macros:

The definition in the example is lexically isolated, and no variable capture can occur. Instead of the function being called using (my-setq:my-setq …), it can be called with just (my-setq …) because it is a default function.

delete ⚠

syntax: (delete symbol [bool])
syntax: (delete sym-context [bool])

In the first syntax deletes a symbol symbol and references to the symbol in other expressions will be changed to nil.

In the second syntax all symbols of the namespace referred to by sym-context will be deleted and references to them in other espressions will be changed to nil. The context symbol sym-context will be changed to a normal symbol containing nil.

When the expression in bool evaluates to true, symbols are only deleted when they are not referenced.

When the expression in bool evaluates to nil, symbols will be deleted without any reference checking. Note that this mode should only be used, if no references to the symbol exist outside it's namespace. If external references exist, this mode can lead to system crashes, as the external reference is not set to nil when using this mode. This mode can be used to delete namespace hashes and to delete namespaces in object systems, where variables are strictly treated as private.

Protected symbols of built-in functions and special symbols like nil and true cannot be deleted.

delete returns true if the symbol was deleted successfully or nil if the symbol was not deleted.

When deleting a context symbol, the first delete removes the context namespace contents and demotes the context symbol to a normal mono-variable symbol. A second delete will remove the symbol from the symbol table.

In the last example only the symbols inside context foo will be deleted but not the context symbol foo itself. It will be converted to a normal unprotected symbol and contain nil.

Note that deleting a symbol that is part of an expression which is currently executing can crash the system or have other unforeseen effects.

delete-file

syntax: (delete-file str-file-name)

Deletes a file given in str-file-name. Returns true if the file was deleted successfully.

On failure the function returns nil. For error information, use sys-error when used on files. When used on URLs net-error gives more error information.

The first example deletes the file junk in the current directory. The second example shows how to use a URL to specify the file. In this form, additional parameters can be given. See delete-url for details.

delete-url

syntax: (delete-url str-url)

This function deletes the file on a remote HTTP server specified in str-url. The HTTP DELETE protocol must be enabled on the target web server, or an error message string may be returned. The target file must also have access permissions set accordingly. Additional parameters such as timeout and custom headers are available exactly as in the get-url function.

This feature is also available when the delete-file function is used and a URL is specified for the filename.

The second example configures a timeout option of five seconds. Other options such as special HTTP protocol headers can be specified, as well. See the get-url function for details.

destroy

syntax: (destroy int-pid)
syntax: (destroy int-pid int-signal)

Destroys a process with process id in int-pid and returns true on success or nil on failure. The process id is normally obtained from a previous call to fork on Mac OS X and other Unix or process on all platforms. On Unix, destroy works like the system utility kill using the SIGKILL signal.

CAUTION! If int-pid is 0 the signal is sent to all processes whose group ID is equal to the process group ID of the sender. If int-pid is -1 all processes with the current user id will be killed, if newLISP is started with super user privileges, all processes except system processes are destroyed.

When specifying int-signal, destroy works like a Unix kill command sending the specified Unix signal to the process in int-pid. This second syntax is not available on MS Windows.

det

syntax: (det matrix [float-pivot])

Returns the determinant of a square matrix. A matrix can either be a nested list or an array.

Optionally 0.0 or a very small value can be specified in float-pivot. This value substitutes pivot elements in the LU-decomposition algorithm, which result in zero when the algorithm deals with a singular matrix.

If the matrix is singular and float-pivot is not specified, nil is returned.

device

syntax: (device [int-io-handle])

int-io-handle is an I/O device number, which is set to 0 (zero) for the default STD I/O pair of handles, 0 for stdin and 1 for stdout. int-io-handle may also be a file handle previously obtained using open. In this case both, input and output are channeled through this handle. When no argument is supplied, the current I/O device number is returned.

The I/O channel specified by device is used internally by the functions print, println, write, write-line and read-char, read-line. When the current I/O device is 0 or 1, print sends output to the console window and read-line accepts input from the keyboard. If the current I/O device has been set by opening a file, then print and read-line work on that file.

Note, that on Unix like operating systems, stdin channel 0 can also be used for output and stdout channel 1 can also be used for reading input. This is not the case on Windows, where 0 is strictly for input and stdout 1 strictly for output.

difference

syntax: (difference list-A list-B)
syntax: (difference list-A list-B bool)

In the first syntax, difference returns the set difference between list-A and list-B. The resulting list only has elements occurring in list-A, but not in list-B. All elements in the resulting list are unique, but list-A and list-B need not be unique. Elements in the lists can be any type of Lisp expression.

In the second syntax, difference works in list mode. bool specifies true or an expression not evaluating to nil. In the resulting list, all elements of list-B are eliminated in list-A, but duplicates of other elements in list-A are left.

directory

syntax: (directory [str-path])
syntax: (directory str-path str-pattern [regex-option])

A list of directory entry names is returned for the directory path given in str-path. On failure, nil is returned. When str-path is omitted, the list of entries in the current directory is returned.

The first example returns the directory of /bin, the second line returns a list of directory entries in the root directory of drive C:. Note that on MS Windows systems, a forward slash (/) can be included in path names. When used, a backslash (\) must be preceded by a second backslash.

In the second syntax, directory can take a regular expression pattern in str-pattern. Only filenames matching the pattern will be returned in the list of directory entries. In regex-option, special regular expression options can be specified; see regex for details.

The regular expression forces directory to return only file names containing the string ".c".

directory?

syntax: (directory? str-path)

Checks if str-path is a directory. Returns true or nil depending on the outcome.

display-html JS

syntax: (display-html str-html)
syntax: (display-html str-html bool-flag)

Using the first syntax, the function replaces the current page in the browser with the HTML page found in str-html.

If bool-flag evaluates to true, the page gets opened in a new browser tab and the current page is not affected.

See also the function eval-string-js for evaluation of JavaScript in the current page.

div

syntax: (div num-1 num-2 [num-3 ... ])
syntax: (div num-1)

Successively divides num-1 by the number in num-2—. div can perform mixed-type arithmetic, but it always returns floating point numbers. Any floating point calculation with NaN also returns NaN.

do-until

syntax: (do-until exp-condition [body])

The expressions in body are evaluated before exp-condition is evaluated. If the evaluation of exp-condition is not nil, then the do-until expression is finished; otherwise, the expressions in body get evaluated again. Note that do-until evaluates the conditional expression after evaluating the body expressions, whereas until checks the condition before evaluating the body. The return value of the do-until expression is the last evaluation of the body expression. If body is empty, the last result of exp-condition is returned.

While do-until goes through the loop at least once, until never enters the loop.

do-while

syntax: (do-while exp-condition body)

The expressions in body are evaluated before exp-condition is evaluated. If the evaluation of exp-condition is nil, then the do-while expression is finished; otherwise the expressions in body get evaluated again. Note that do-while evaluates the conditional expression after evaluating the body expressions, whereas while checks the condition before evaluating the body. The return value of the do-while expression is the last evaluation of the body expression.

While do-while goes through the loop at least once, while never enters the loop.

doargs

syntax: (doargs (sym [exp-break]) body)

Iterates through all members of the argument list inside a user-defined function or macro. This function or macro can be defined using define, define-macro, lambda, or lambda-macro. The variable in sym is set sequentially to all members in the argument list until the list is exhausted or an optional break expression (defined in exp-break) evaluates to true or a logical true value. The doargs expression always returns the result of the last evaluation.

The optional break expression causes doargs to interrupt processing of the arguments:

dolist

syntax: (dolist (sym list|array [exp-break]) body)

The expressions in body are evaluated for each element in list or array. The variable in sym is set to each of the elements before evaluation of the body expressions. The variable used as loop index is local and behaves according to the rules of dynamic scoping.

Optionally, a condition for early loop exit may be defined in exp-break. If the break expression evaluates to any non-nil value, the dolist loop returns with the value of exp-break. The break condition is tested before evaluating body.

This example prints abcdefg in the console window. After the execution of dolist, the value for x remains unchanged because the x in dolist has local scope. The return value of dolist is the result of the last evaluated expression.

The internal system variable $idx keeps track of the current offset into the list passed to dolist, and it can be accessed during its execution:

The console output is shown in boldface. $idx is protected and cannot be changed by the user.

dostring utf8

syntax: (dostring (sym string [exp-break]) body)

The expressions in body are evaluated for each character in string. The variable in sym is set to each ASCII or UTF-8 integer value of the characters before evaluation of the body expressions. The variable used as loop index is local and behaves according to the rules of dynamic scoping.

This example prints the value of each character in the console window. In UTF-8 enabled versions of newLISP, individual characters may be longer than one byte and the number in the loop variable may exceed 255. The return value of dostring is the result of the last evaluated expression.

The internal system variable $idx keeps track of the current offset into the string passed to dostring, and it can be accessed during its execution.

dotimes

syntax: (dotimes (sym-var int-count [exp-break]) body)

The expressions in body are evaluated int times. The variable in sym is set from 0 (zero) to (int - 1) each time before evaluating the body expression(s). The variable used as the loop index is local to the dotimes expression and behaves according the rules of dynamic scoping. The loop index is of integer type. dotimes returns the result of the last expression evaluated in body. After evaluation of the dotimes statement sym assumes its previous value.

Optionally, a condition for early loop exit may be defined in exp-break. If the break expression evaluates to any non-nil value, the dotimes loop returns with the value of exp-break. The break condition is tested before evaluating body.

dotree

syntax: (dotree (sym sym-context [bool]) body)

The expressions in body are evaluated for all symbols in sym-context. The symbols are accessed in a sorted order. Before each evaluation of the body expression(s), the variable in sym is set to the next symbol from sym-context. The variable used as the loop index is local to the dotree expression and behaves according the rules of dynamic scoping.

When the optional bool expression evaluates to not nil, only symbols starting with an underscore character _ are accessed. Symbol names starting with an _ underscore are used for hash keys and symbols created by bayes-train.

This example prints the names of all symbols inside SomeCTX to the console window.

dump

syntax: (dump [exp])

Shows the binary contents of a newLISP cell. Without an argument, this function outputs a listing of all Lisp cells to the console. When exp is given, it is evaluated and the contents of a Lisp cell are returned in a list.

offset	description
0	memory address of the newLISP cell
1	cell->type: major/minor type, see newlisp.h for details
2	cell->next: linked list ptr
3	cell->aux: string length+1 or low (little endian) or high (big endian) word of 64-bit integer or low word of IEEE 754 double float
4	cell->contents: string/symbol address or high (little endian) or low (big endian) word of 64-bit integer or high word of IEEE 754 double float

This function is valuable for changing type bits in cells or hacking other parts of newLISP internals. See the function cpymem for a comprehensive example.

dup

syntax: (dup exp int-n [bool])
syntax: (dup exp)

If the expression in exp evaluates to a string, it will be replicated int-n times within a string and returned. When specifying an expression evaluating to anything other than nil in bool, the string will not be concatenated but replicated in a list like any other data type.

If exp contains any data type other than string, the returned list will contain int-n evaluations of exp.

The last example shows handling of binary information, creating a string filled with four binary zeroes.

empty?

syntax: (empty? exp)
syntax: (empty? str)

exp is tested for an empty list (or str for an empty string). Depending on whether the argument contains elements, true or nil is returned.

encrypt

syntax: (encrypt str-source str-pad)

Performs a one-time pad (OTP) encryption of str-source using the encryption pad in str-pad. The longer str-pad is and the more random the bytes are, the safer the encryption. If the pad is as long as the source text, is fully random, and is used only once, then one-time–pad encryption is virtually impossible to break, since the encryption seems to contain only random data. To retrieve the original, the same function and pad are applied again to the encrypted text:

ends-with

syntax: (ends-with str-data str-key [num-option])
syntax: (ends-with list exp)

In the first syntax, ends-with tests the string in str-data to see if it ends with the string specified in str-key. It returns true or nil depending on the outcome.

If a regular expression option number is specified, str-key contains a regular expression pattern. See regex for valid numbers for option.

In the second syntax, ends-with checks if a list ends with the list element in exp. true or nil is returned depending on outcome.

env

syntax: (env)
syntax: (env var-str)
syntax: (env var-str value-str)

In the first syntax (without arguments), the operating system's environment is retrieved as an association list in which each entry is a key-value pair of environment variable and value.

In the second syntax, the name of an environment variable is given in var-str. env returns the value of the variable or nil if the variable does not exist in the environment.

The third syntax (variable name in var-str and value pair in value-str) sets or creates an environment variable. If value-str is the empty string "", then the variable is completely removed from the environment except when running on Solaris, where the variable stays with an empty string.

erf

syntax: (erf num)

erf calculates the error function of a number in num. The error function is defined as:

error-event

syntax: (error-event sym-event-handler | func-event-handler)
syntax: (error-event nil)

sym-event-handler contains a user-defined function for handling errors. Whenever an error occurs, the system performs a reset and executes the user-defined error handler. The error handler can use the built-in function last-error to retrieve the number and text of the error. The event handler is specified as either a quoted symbol or a lambda function.

For a different way of handling errors, see the catch function. Use throw-error to throw user-defined errors.

eval

syntax: (eval exp)

eval evaluates the result of evaluating exp in the current variable environment.

newLISP passes all arguments by value. Using a quoted symbol, expressions can be passed by reference through the symbol. eval can be used to access the original contents of the symbol:

In the example, the parameter 'data is quoted, so push can work on the original list.

There is a safer method to pass arguments by reference in newLISP by enclosing the data inside context objects. See the chapter Passing data by reference. Passing references into user defined function using namespace ids avoids variable capture of the passed symbol, in case the symbol passed is the same used as a parameter in the function.

eval-string

syntax: (eval-string str-source [sym-context [exp-error [int-offset]]])

The string in str-source is compiled into newLISP's internal format and then evaluated. The evaluation result is returned. If the string contains more than one expression, the result of the last evaluation is returned.

An optional second argument can be used to specify the context to which the string should be parsed and translated.

If an error occurs while parsing and evaluating str-source then exp-error will be evaluated and the result returned.

int-offset specifies an optional offset into str-source, where to start evaluation.

The last example shows how to specify a target context for translation. The symbols a and b now refer to symbols and their values in context foo instead of MAIN.

See also the function read-expr which translates a string without evaluating it.

eval-string-js JS

syntax: (eval-string-js str-JavaScript-source)

The function takes a program source in str-JavaScript-source and returns the result in a string.

The first expression will pop up a dialog box to enter text. The function will return the text string entered. The second expression will return the string 42.

even? bigint

syntax: (even? int-number)

Checks if an integer number is even divisible by 2, without remainder. When a floating point number is passed for int-number, it will be converted to an integer by cutting off its fractional part.

exec

syntax: (exec str-process)
syntax: (exec str-process [str-stdin])

In the first form, exec launches a process described in str-process and returns all standard output as a list of strings (one for each line in standard out (STDOUT)). exec returns nil if the process could not be launched. If the process could be launched but only returns and error and no valid output, the empty list will be returned.

The example starts a process and performs the shell command ls, capturing the output in an array of strings.

In the second form, exec creates a process pipe, starts the process in str-process, and receives from str-stdin standard input for this process. The return value is true if the process was successfully launched; otherwise it is nil.

In this example, cgiProc could be a cgi processor (e.g., Perl or newLISP) that receives and processes standard input supplied by a string contained in the variable query.

exists

syntax: (exists func-condition list)

Successively applies func-condition to the elements of list and returns the first element that meets the condition in func-condition. If no element meets the condition, nil is returned.

If func-condition is nil?, the result nil is ambiguous. In this case index or find are the better method when looking for nil.

Use the for-all function to check if a condition is met for all elements in a list.

exit

syntax: (exit [int])

Exits newLISP. An optional exit code, int, may be supplied. This code can be tested by the host operating system. When newLISP is run in daemon server mode using -d as a command-line option, only the network connection is closed, while newLISP stays resident, listening for a new connection.

exp

syntax: (exp num)

The expression in num is evaluated, and the exponential function is calculated based on the result. exp is the inverse function of log.

expand

syntax: (expand exp sym-1 [sym-2 ... ])
syntax: (expand exp list-assoc [bool])
syntax: (expand exp)

In the first syntax, one symbol in sym (or more in sym-2 through sym-n) is looked up in a simple or nested expression exp. They are then expanded to the current binding of the symbol and the expanded expression is returned. The original list remains unchanged.

expand is useful when composing lambda expressions and doing variable expansion as in rewrite macros.

If more than one symbol is present, expand will work in an incremental fashion:

syntax: (expand list list-assoc [bool])

The second syntax of expand allows expansion bindings to be specified on the fly, without performing a set on the participating variables:

If the bool evaluates to true, the value parts in the association list are evaluated.

Note that the contents of the variables in the association list will not change. This is different from the letex function, where variables are set by evaluating and assigning their association parts.

This form of expand is frequently used in logic programming, together with the unify function.

syntax: (expand list)

A third syntax is used to expand only the contents of variables starting with an uppercase character. This PROLOG mode may also be used in the context of logic programming. As in the first syntax of expand, symbols must be preset. Only uppercase variables and those bound to anything other than nil will be expanded:

Only the symbols A and Bvar are expanded because they have capitalized names and non-nil contents.

The currying function in the example demonstrating the first syntax of expand can now be written even more simply using an uppercase variable:

See the letex function, which also provides an expansion mechanism, and the function unify, which is frequently used together with expand.

explode utf8

syntax: (explode str [int-chunk [bool]])
syntax: (explode list [int-chunk [bool]])

In the first syntax, explode transforms the string (str) into a list of single-character strings. Optionally, a chunk size can be specified in int-chunk to break the string into multi-character chunks. When specifying a value for bool other than nil, the last chunk will be omitted if it does not have the full length specified in int-chunk.

When called in UTF-8–enabled versions of newLISP, explode will work on character boundaries rather than byte boundaries. In UTF-8–encoded strings, characters may contain more than one byte. Processing will stop when a zero byte character is found.

To explode binary contents on UTF-8–enabled versions of newLISP use unpack as shown in the following example:

In the second syntax, explode explodes a list (list) into sublists of chunk size int-chunk, which is 1 (one) by default.

The following shows an example of the last chunk being omitted when the value for bool is other than nil, and the chunk does not have the full length specified in int-chunk.

extend !

syntax: (extend list-1 [list-2 ... ])
syntax: (extend string-1 [string-2 ... ])

The list in list-1 is extended by appending list-2. More than one list may be appended.

The string in string-1 is extended by appending string-2. More than one string may be appended. The string can contain binary 0 (zero) characters.

factor

syntax: (factor int)

Factors the number in int into its prime components. When floating point numbers are passed, they are truncated to their integer part first.

factor returns nil for numbers smaller than 2. For numbers larger than 9,223,372,036,854,775,807 (the largest 64-bit integer) converted from floating point numbers, the largest integer is factored.

fft

syntax: (fft list-num)

Calculates the discrete Fourier transform on the list of complex numbers in list-num using the FFT method (Fast Fourier Transform). Each complex number is specified by its real part followed by its imaginary part. If only real numbers are used, the imaginary part is set to 0.0 (zero). When the number of elements in list-num is not a power of 2, fft increases the number of elements by padding the list with zeroes. When the imaginary part of a complex number is 0, simple numbers can be used instead.

file-info

syntax: (file-info str-name [int-index [bool-flag]])

Returns a list of information about the file or directory in str_name. The optional index specifies the list member to return. When no bool-flag is specified or when bool-flag evaluates to nil information about the link is returned if the file is a link to an original file. If bool-flag evaluates to anything else than nil, information about the original file referenced by the link is returned.

offset	contents
0	size
1	mode (differs with `true` flag)
2	device mode
3	user ID
4	group ID
5	access time
6	modification time
7	status change time

Depending on bool-flag set, the function reports on either the link (no flag or nil flag) or on the original linked file (true flag).

In the second example, the last status change date for the directory /etc is retrieved.

file-info gives file statistics (size) for a linked file, not the link, except for the mode field.

file?

syntax: (file? str-path-name [bool])

Checks for the existence of a file in str-name. Returns true if the file exists; otherwise, it returns nil. This function will also return true for directories. If the optional bool value is true, the file must not be a directory and str-path-name is returned or nil if the file is a directory. The existence of a file does not imply anything about its read or write permissions for the current user.

filter

syntax: (filter exp-predicate exp-list)

The predicate exp-predicate is applied to each element of the list exp-list. A list is returned containing the elements for which exp-predicate is true. filter works like clean, but with a negated predicate.

The predicate may be a built-in predicate, a user-defined function, or a lambda expression.

For filtering a list of elements with the elements from another list, use the difference function or intersect (with the list option).

See also the related function index, which returns the indices of the filtered elements and clean, which returns all elements of a list for which a predicate is false.

find

syntax: (find exp-key list [func-compare | regex-option])
syntax: (find str-key str-data [regex-option [int-offset]])

Find an expression in a list

If the second argument evaluates to a list, then find returns the index position (offset) of the element derived from evaluating exp-key.

Optionally, an operator or user-defined function can be specified in func-compare. If the exp-key is a string, a regular expression option can be specified with the regex-option parameter.

When using regular expressions or comparison functors the system variable $0 is set to the last element found.

Using match and unify, list searches can be formulated which are as powerful as regular expression searches are for strings.

Find a string in a string

If the second argument, str-data, evaluates to a string, then the offset position of the string str-key (found in the first argument, str-data) is returned. In this case, find also works on binary str-data. The offset position returned is always based on counting single byte characters even when running the UTF-8 enabled version of newLISP.

The presence of a third parameter specifies a search using the regular expression pattern specified in str-pattern, as well as an option number specified in regex-option (i.e., 1 (one) for case-insensitive search or 0 (zero) for no special options). If regex-option is specified an optional int-offset argument can be specified too to start the search not at the beginning but at the offset given. In any case the position returned by find is calculated relative to the beginning of the string.

To specify int-offset in a simple string search without regular expressions, specify nil for regex-option.

In newLISP, regular expressions are standard Perl Compatible Regular Expression (PCRE) searches. Found expressions or subexpressions are returned in the system variables $0, $1, $2, etc., which can be used like any other symbol. As an alternative, the contents of these variables can also be accessed by using ($ 0), ($ 1), ($ 2), etc. This method allows indexed access (i.e., ($ i), where i is an integer).

See regex for the meaning of the option numbers and more information on regular expression searching.

To find expressions in nested or multidimensional lists, use the ref and ref-all functions.

find-all

syntax: (find-all str-regex-pattern str-text [exp [regex-option]])
syntax: (find-all list-match-pattern list [exp])
syntax: (find-all exp-key list [exp [func-compare]])

In the first syntax, find-all finds all occurrences of str-regex-pattern in the text str-text, returning a list containing all matching strings. The empty list () is returned if no matches are found. In the first syntax string searches are always done using regular expression patterns, even if no regex-option is specified. The system variable $count is updated with the number of matches found.

Optionally, an expression can be specified to process the found string or regular subexpressions before placing them into the returned list. An additional option, regex-option, specifies special regular expression options (see regex for further details).

The first example discovers all numbers in a text. The second example shows how an optional expression in exp can work on subexpressions found by the regular expression pattern in str-pattern. The last example retrieves a web page, cleans out all HTML tags, and then collects all words into a unique and sorted list.

Note that find-all with strings always performs a regular expression search, even if the option in regex-option is omitted.

In the second syntax, find-all searches for all list match patterns list-match-pattern in list. As in find-all for strings, an expression can be specified in exp to process further the matched sublist found in list. The system variable $count is updated with the number of matches found.

find-all for list matches always uses match to compare when searching for sublists and always needs a list for the pattern expression.

In the third syntax, find-all can specify a built-in or user-defined function used for comparing list elements with the key expression in exp-key:

Any type of expression can be searched for or can be contained in the list. find-all in this syntax works similar to filter but with the added benefit of being able to define a processing expression for the found element.

If no func-compare is defined and exp-key is a list, then match will be used for comparison, as in the second syntax.

first utf8

syntax: (first list)
syntax: (first array)
syntax: (first str)

Returns the first element of a list or the first character of a string. The operand is not changed. This function is equivalent to car or head in other Lisp dialects.

In the third syntax, the first character is returned from the string in str as a string.

Note that first works on character boundaries rather than byte boundaries when the UTF-8–enabled version of newLISP is used. See also the functions last and rest.

flat

syntax: (flat list [int-level])

The optional int-level parameter can be used to limit the recursion level when flattening the list:

float

syntax: (float exp [exp-default])

If the expression in exp evaluates to a number or a string, the argument is converted to a float and returned. If exp cannot be converted to a float then nil or, if specified, the evaluation of exp-default will be returned. This function is mostly used to convert strings from user input or when reading and parsing text. The string must start with a digit or the + (plus sign), - (minus sign), or . (period). If exp is invalid, float returns nil as a default value.

Floats with exponents larger than 1e308 or smaller than -1e308 are converted to +INF or -INF, respectively. The display of +INF and -INF differs on different platforms and compilers.

float?

syntax: (float? exp)

true is returned only if exp evaluates to a floating point number; otherwise, nil is returned.

floor

syntax: (floor number)

flt

syntax: (flt number)

Converts number to a 32-bit float represented by an integer. This function is used when passing 32-bit floats to library routines. newLISP floating point numbers are 64-bit and are passed as 64-bit floats when calling imported C library routines.

syntax: (fn (list-parameters) exp-body)

fn or lambda are used to define anonymous functions, which are frequently used in map, sort, and all other expressions where functions can be used as arguments. The fn or lambda word does not exist on its own as a symbol, but indicates a special list type: the lambda list. Together with fn-macro and lambda-macro these terms are recognized during source parsing. They indicate a specialized type of list which can be used and applied like a function or operator.

Using an anonymous function eliminates the need to define a new function with define. Instead, a function is defined on the fly:

The example defines the function fn(x), which takes an integer (x) and doubles it. The function is mapped onto a list of arguments using map. The second example shows strings being sorted by length.

The lambda function (the longer, traditional form of writing) can be used in place of fn.

for

syntax: (for (sym num-from num-to [num-step [exp-break]]) body)

Repeatedly evaluates the expressions in body for a range of values specified in num-from and num-to, inclusive. A step size may be specified with num-step. If no step size is specified, 1 is assumed.

Optionally, a condition for early loop exit may be defined in exp-break. If the break expression evaluates to any non-nil value, the for loop returns with the value of exp-break. The break condition is tested before evaluating body. If a break condition is defined, num-step must be defined, too.

The symbol sym is local in dynamic scope to the for expression. It takes on each value successively in the specified range as an integer value if no step size is specified, or as a floating point value when a step size is present. After evaluation of the for statement sym assumes its previous value.

The second example uses a range of numbers from highest to lowest. Note that the step size is always a positive number. In the third example, a break condition is tested.

for-all

syntax: (for-all func-condition list)

Applies the function in func-condition to all elements in list. If all elements meet the condition in func-condition, the result is true; otherwise, nil is returned.

Use the exists function to check if at least one element in a list meets a condition.

fork

syntax: (fork exp)

The expression in exp is launched as a newLISP child process-thread of the platforms OS. The new process inherits the entire address space, but runs independently so symbol or variable contents changed in the child process will not affect the parent process or vice versa. The child process ends when the evaluation of exp finishes.

On success, fork returns with the child process ID; on failure, nil is returned. See also the wait-pid function, which waits for a child process to finish.

This function is only available on Linux/Unix versions of newLISP and is based on the fork() implementation of the underlying OS.

A much simpler automated method to launch processes and collect results is available with spawn and the Cilk API.

The example illustrates how the child process-thread inherits the symbol space and how it is independent of the parent process. The fork statement returns immediately with the process ID 176. The child process increments the variable x by one each second and prints it to standard out (boldface). In the parent process, commands can still be entered. Type x to see that the symbol x still has the value 0 (zero) in the parent process. Although statements entered will mix with the display of the child process output, they will be correctly input to the parent process.

The second example illustrates how pipe can be used to communicate between processes.

The count-down-proc writes numbers to the communication pipe, where they are picked up by the observer-process and displayed.

A forked process can either exit by itself or it can be destroyed using the destroy function.

The process started by fork-destroy-demo will not finish but is destroyed 50 milli-seconds after start by a call to destroy.

Use the semaphore function for synchronizing processes and share for sharing memory between processes.

See spawn for a much simpler and automated way to synchronize processes and collect results.

format

syntax: (format str-format exp-data-1 [exp-data-2 ... ])
syntax: (format str-format list-data)

Constructs a formatted string from exp-data-1 using the format specified in the evaluation of str-format. The format specified is identical to the format used for the printf() function in the ANSI C language. Two or more exp-data arguments can be specified for more than one format specifier in str-format.

In an alternative syntax, the data to be formatted can be passed inside a list in list-data.

format checks for a valid format string, matching data type, and the correct number of arguments. Wrong formats or data types result in error messages. int, float, or string can be used to ensure correct data types and to avoid error messages.

The % (percent sign) starts a format specification. To display a % inside a format string, double it: %%

On Linux the percent sign can be followed by a single quote %' to insert thousand's separators in number formats.

The w represents the width field. Data is right-aligned, except when preceded by a minus sign, in which case it is left-aligned. If preceded by a + (plus sign), positive numbers are displayed with a +. When preceded by a 0 (zero), the unused space is filled with leading zeroes. The width field is optional and serves all data types.

The p represents the precision number of decimals (floating point only) or strings and is separated from the width field by a period. Precision is optional. When using the precision field on strings, the number of characters displayed is limited to the number in p.

format	description
s	text string
c	character (value 1 - 255)
d	decimal (32-bit)
u	unsigned decimal (32-bit)
x	hexadecimal lowercase
X	hexadecimal uppercase
o	octal (32-bits) (not supported on all of newLISP flavors)
f	floating point
e	scientific floating point
E	scientific floating point
g	general floating point

Formatting 64-bit numbers using the 32-bit format specifiers from above table will truncate and format the lower 32 bits of the number on 64-bit systerms and overflow to 0xFFFFFFFF on 32-bit systems.

For 32-bit and 64-bit numbers use the following format strings. 64-bit numbers will be truncated to 32-bit on 32-bit platforms:

For 64-bit numbers use the following format strings on Unix-like operating systems and on MS Windows (not supported on TRU64):

format	description
ld	decimal (32/64-bit)
lu	unsigned decimal (32/64-bit)
lx	hexadecimal (32/64-bit)
lX	hexadecimal uppercase (32/64-bit)

format	description
lld	decimal (64-bit)
llu	unsigned decimal (64-bit)
llx	hexadecimal (64-bit)
llX	hexadecimal uppercase(64-bit)

format	description
I64d	decimal (64-bit)
I64u	unsigned decimal (64-bit)
I64x	hexadecimal (64-bit)
I64X	hexadecimal uppercase(64-bit)

If the format string requires it, newLISP's format will automatically convert integers into floating points or floating points into integers:

syntax: (fv num-rate num-nper num-pmt num-pv [int-type])

Calculates the future value of a loan with constant payment num-pmt and constant interest rate num-rate after num-nper period of time and a beginning principal value of num-pv. If payment is at the end of the period, int-type is 0 (zero) or int-type is omitted; for payment at the beginning of each period, int-type is 1.

The example illustrates how a loan of $100,000 is paid down to a residual of $0.55 after 240 monthly payments at a yearly interest rate of 7 percent.

gammai

syntax: (gammai num-a num-b)

Calculates the incomplete Gamma function of values a and b in num-a and num-b, respectively.

The incomplete Gamma function is used to derive the probability of Chi² to exceed a given value for a degree of freedom, df, as follows:

gammaln

syntax: (gammaln num-x)

The example uses the equality of n! = gamma(n + 1) to calculate the factorial value of 5.

The log Gamma function is also related to the Beta function, which can be derived from it:

gcd bigint

syntax: (gcd int-1 [int-2 ... ])

Calculates the greatest common divisor of a group of integers. The greatest common divisor of two integers that are not both zero is the largest integer that divides both numbers. gcd will calculate the greatest common divisor for the first two integers in int-i and then further reduce the argument list by calculating the greatest common divisor of the result and the next argument in the parameter list.

get-char ⚠

syntax: (get-char int-address)

Gets an 8-bit character from an address specified in int-address. This function is useful when using imported shared library functions with import.

Consider the above C function from a shared library, which returns a character pointer (address to a string).

Note that it is unsafe to use the get-char function with an incorrect address in int-address. Doing so could result in the system crashing or becoming unstable.

get-float ⚠

syntax: (get-float int-address)

Gets a 64-bit double float from an address specified in int-address. This function is helpful when using imported shared library functions (with import) that return an address pointer to a double float or a pointer to a structure containing double floats.

foo is imported and returns a pointer to a double float when called. Note that get-float is unsafe when used with an incorrect address in int-address and may result in the system crashing or becoming unstable.

get-int ⚠

syntax: (get-int int-address)

Gets a 32-bit integer from the address specified in int-address. This function is handy when using imported shared library functions with import, a function returning an address pointer to an integer, or a pointer to a structure containing integers.

Consider the C function foo (from a shared library), which returns an integer pointer (address of an integer).

Note that using get-int with an incorrect address in int-address is unsafe and could result in the system crashing or becoming unstable.

get-long ⚠

syntax: (get-long int-address)

Gets a 64-bit integer from the address specified in int-address. This function is handy when using import to import shared library functions, a function returning an address pointer to a long integer, or a pointer to a structure containing long integers.

Consider the C function foo (from a shared library), which returns an integer pointer (address of an integer).

Note that using get-long with an incorrect address in int-address is unsafe and could result in the system crashing or becoming unstable.

get-string ⚠

syntax: (get-string int-address [int-bytes [str-limit])

Copies a character string from the address specified in int-address. This function is helpful when using imported shared library functions with import and a C-function returns the address to a memory buffer.

Consider the above C function from a shared library, which returns a character pointer (address to a string).

When a string is passed as an argument, get-string will take its address as the argument. Without the optional int-bytes argument get-string breaks off at the first first \000 (null character) it encounters. This works for retrieving ASCII strings from raw memory addresses:

When specifyung the number of bytes in the optional int-bytes parameter, reading does not stpop at the first zero byte found, but copies exactly int-bytes number of bytes from the address or string buffer:

The addtional str-limit parameter can be used to limit reading the buffer at a certain string. If int-bytes are read before str-limit is found, only int-bytes are read:

Although UTF-16 and UTF-32 encoding does not specify string termination characters, the sequences "\000\000" and "\000\000\000\000" are used often to terminate UTF-16 and UTF-32 encodings. The additional optional str-limit can be used to limit the string when reading from the buffer address:

When using "\000\000" or "\000\000\000\000" as limit strings, the search for these limits is aligned to a 2-byte or 4-byte border.

Note that get-string can crash the system or make it unstable if the wrong address is specified.

get-url

syntax: (get-url str-url [str-option] [int-timeout [str-header]])

Reads a web page or file specified by the URL in str-url using the HTTP GET protocol. Both http:// and file:// URLs are handled. "header" can be specified in the optional argument str-option to retrieve only the header. The option "list" causes header and page information to be returned as separate strings in a list and also includes the server status code as the third list member (since 10.6.4). The "raw" option (since 10.6.4), which can be used alone or combined with other options, suppresses header location redirection.

A "debug" option can be specified either alone or after the "header" or "list" option separated by one character, i.e. "header debug" or "list debug". Including "debug" outputs all outgoing information to the console window.

The optional argument int-timeout can specify a value in milliseconds. If no data is available from the host after the specified timeout, get-url returns the string ERR: timeout. When other error conditions occur, get-url returns a string starting with ERR: and the description of the error.

get-url handles redirection if it detects a Location: spec in the received header and automatically does a second request. get-url also understands the Transfer-Encoding: chunked format and will unpack data into an unchunked format.

The index page from the site specified in str-url is returned as a string. In the third line, only the HTTP header is returned in a string. Lines 2 and 4 show a timeout value being used.

The second example shows usage of a file:// URL to access /home/db/data.txt on the local file system.

The third example illustrates the use of a proxy server. The proxy server's URL must be in the operating system's environment. As shown in the example, this can be added using the env function.

Custom header

The custom header may contain options for browser cookies or other directives to the server. When no str-header is specified, newLISP sends certain header information by default. After the following request:

Note that when using a custom header, newLISP will only supply the GET request line, as well as the Host: and Connection: header entries. newLISP inserts all other entries supplied in the custom header between the Host: and Connection: entries. Each entry must end with a carriage return line-feed pair: \r\n.

global

syntax: (global sym-1 [sym-2 ... ])

One or more symbols in sym-1 [sym-2 ... ] can be made globally accessible from contexts other than MAIN. The statement has to be executed in the MAIN context, and only symbols belonging to MAIN can be made global. global returns the last symbol made global.

The second example shows how constant and global can be combined into one statement, protecting and making a previous function definition global.

global?

syntax: (global? sym)

Checks if symbol in sym is global. Built-in functions, context symbols, and all symbols made global using the function global are global:

syntax: (if exp-condition exp-1 [exp-2])
syntax: (if exp-cond-1 exp-1 exp-cond-2 exp-2 [ ... ])

If the value of exp-condition is neither nil nor an empty list, the result of evaluating exp-1 is returned; otherwise, the value of exp-2 is returned. If exp-2 is absent, the value of exp-condition is returned.

if also sets the anaphoric system variable $it to the value of the conditional expression in if.

The second form of if works similarly to cond, except it does not take parentheses around the condition-body pair of expressions. In this form, if can have an unlimited number of arguments.

The last expression, "n/a", is optional. When this option is omitted, the evaluation of (>= x 30) is returned, behaving exactly like a traditional cond but without requiring parentheses around the condition-expression pairs.

In any case, the whole if expression always returns the last expression or condition evaluated.

ifft

syntax: (ifft list-num)

Calculates the inverse discrete Fourier transform on a list of complex numbers in list-num using the FFT method (Fast Fourier Transform). Each complex number is specified by its real part, followed by its imaginary part. In case only real numbers are used, the imaginary part is set to 0.0 (zero). When the number of elements in list-num is not an integer power of 2, ifft increases the number of elements by padding the list with zeroes. When complex numbers are 0 in the imaginary part, simple numbers can be used.

import ⚠

syntax: (import str-lib-name str-function-name ["cdecl"])
syntax: (import str-lib-name str-function-name str-return-type [str-param-type . . .])
syntax: (import str-lib-name)

Imports the function specified in str-function-name from a shared library named in str-lib-name. Depending on the syntax used, string labels for return and parameter types can be specified

If the library in str-lib-name is not in the system's library path, the full path name should be specified.

A function can be imported only once. A repeated import of the same function will simply return the same - already allocated - function address.

Note, that the first simple syntax is available on all versions of newLISP, even those compiled without libffi support. On libffi enabled versions - capable of the second extended syntax - imported symbols are protected against change and can only be modified using constant.

The third syntax - on OSX, Linux and other Unix only - allows pre-loading libraries without importing functions. This is necessary when other library imports need access internally to other functions from pre-loaded libraries.

Incorrectly using import can cause a system bus error or a segfault can occur and crash newLISP or leave it in an unstable state.

The simple import syntax

Most library functions can be imported using the simpler first syntax. This form is present on all compile flavors of newLISP. The API expects all function arguments to be passed on the stack in either cdecl or stdcall conventions. On 32-bit platforms, integers, pointers to strings and buffers sometimes floating point values can be passed as parameters. On 64-bit platforms only integers can be passed but no floating point values. As return values only 32-bit or 64-bit values and pointers are allowed. No floating point numbers can be returned. Strings must be retrieved with the get-string helper function. Regardless of these limitations, most modules included in the distribution use this simple import API.

To pass pointers for data structures the following functions help to pack data and calculate addresses: address, pack.

To transform newLISP data types into the data types needed by the imported function, use the functions float for 64-bit double floats, flt for 32-bit floats, and int for 32-bit integers. By default, newLISP passes floating point numbers as 64-bit double floats, integers as 32-bit integers, and strings as 32-bit integers for string addresses (pointers in C). Floats can only be used with 32-bit versions of newLISP and libraries. To use floating point numbers in a 64-bit environment use the extended import syntax.

In the first example, the string "1.23 hello 999 A" is printed as a side effect, and the value 17 (number of characters printed) is returned. Any C function can be imported from any shared library in this way.

The message box example pops up a Windows dialog box, which may be hidden behind the console window. The console prompt does not return until the 'OK' button is pressed in the message box.

The other examples show several imports of MS Windows DLL functions and the details of passing values by value or by reference. Whenever strings or numbers are passed by reference, space must be reserved beforehand.

import returns the address of the function, which can be used to assign a different name to the imported function.

The MS Windows and Cygwin versions of newLISP uses standard call stdcall conventions to call DLL library routines by default. This is necessary for calling DLLs that belong to the MS Windows operating system. Most third-party DLLs are compiled for C declaration cdecl calling conventions and may need to specify the string "cdecl" as an additional last argument when importing functions. newLISP compiled for Mac OS X, Linux and other Unix systems uses the cdecl calling conventions by default and ignores any additional string.

Imported functions may take up to fourteen arguments. Note that floating point arguments take up two spaces each (e.g., passing five floats takes up ten of the fourteen parameters).

The extended import syntax

The extended import API works with the second syntax. It is based on the popular libffi library which is pre-installed on most OS platforms. The startup banner of newLISP should show the word libffi indicating the running version of newLISP is compiled to use the extended import API. The function sys-info can also be used to check for libffi-support.

The API works with all atomic C data types for passed parameters and return values. The extended API requires that parameter types are specified in the import statement as string type labels. Programs written with extended import API will run without change on 32-bit and 64-bit newLISP and libraries. Integers, floating point values and strings can be returned without using helper functions.

The following types can be specified for the return value in str-return-type and for function parameters in str-param-type:

label	C type for return value and arguments	newLISP return and argument type
"void"	void	`nil` is returned for return type
"byte"	byte unsigned 8 bit	integer
"char"	char signed 8 bit	integer
"unsigned short int"	unsigned short int 16 bit	integer
"short int"	short int signed 16 bit	integer
"unsigned int"	unsigned int 32 bit	integer
"int"	int signed 32 bit	integer
"long"	long signed 32 or 64 bit depending on platform	integer
"long long"	long long signed 64 bit	integer
"float"	float 32 bit	IEEE-754 64 bit float cut to 32-bit precision
"double"	double 64 bit	IEEE-754 64 bit float
"char*"	char* 32 or 64 bit ptr depending on platform	displayable string return (zero terminated) string buffer arg (no addr. since 10.4.2)
"void*"	void* 32 or 64 bit ptr depending on platform	integer address return either string buffer or integer address arg

The types "char*" and "void* can be interchanged and are treated identical inside libffi. Depending on the type of arguments passed and the type of return values, one or the other is used.

Aggregate types can be composed using the struct function and can be used for arguments and return values.

The following examples show how the extended import syntax can handle return values of floating point values and strings:

The char* type takes a string buffer only. The "void* type can take either a string buffer or a memory address number as input. When using "void*" as a return type the address number of the result buffer will be returned. This is useful when returning pointers to data structures. These pointers can then be used with unpack and struct for destructuring. In the following example the return type is changed to void*:

Memory management

Any allocation performed by imported foreign functions has to be de-allocated manually if there's no call in the imported API to do so. See the Code Patterns in newLISP document for an example.

In case of calling foreign functions with passing by reference, memory for variables needs to be allocated beforehand by newLISP — see import of GetWindowsDirectoryA above — and hence, memory needs not be deallocated manually, because it is managed automatically by newLISP.

inc !

syntax: (inc place [num])

Increments the number in place by 1.0 or by the optional number num and returns the result. inc performs float arithmetic and converts integer numbers passed into floating point type.

place is either a symbol or a place in a list structure holding a number, or a number returned by an expression.

Places in a list structure or a number returned by another expression can be updated too:

Use the ++ function for incrementing numbers in integer mode. Use dec to decrement numbers in floating point mode.

index

syntax: (index exp-predicate exp-list)

Applies the predicate exp-predicate to each element of the list exp-list and returns a list containing the indices of the elements for which exp-predicate is true.

The predicate may be a built-in predicate, a user-defined function, or a lambda expression.

inf?

syntax: (inf? float)

Note that an integer division by zero e.g. (/ 1 0) will throw an "division by zero" error and not yield infinity. See also NaN? to check if a floating point number is valid.

int

syntax: (int exp [exp-default [int-base]])

If the expression in exp evaluates to a number or a string, the result is converted to an integer and returned. If exp cannot be converted to an integer, then nil or the evaluation of exp-default will be returned. This function is mostly used when translating strings from user input or from parsing text. If exp evaluates to a string, the string must start with a digit; one or more spaces; or the + or - sign. The string must begin with '0x' for hexadecimal strings or '0' (zero) for octal strings. If exp is invalid, int returns nil as a default value if not otherwise specified.

A second optional parameter can be used to force the number base of conversion to a specific value.

Integers larger than 9,223,372,036,854,775,807 are truncated to 9,223,372,036,854,775,807. Integers smaller than -9,223,372,036,854,775,808 are truncated to -9,223,372,036,854,775,808.

When converting from a float (as in the second form of int), floating point values larger or smaller than the integer maximum or minimum are also truncated. A floating point expression evaluating to NaN is converted to 0 (zero).

integer?

syntax: (integer? exp)

Returns true only if the value of exp is an integer; otherwise, it returns nil.

intersect

syntax: (intersect list-A list-B)
syntax: (intersect list-A list-B bool)

In the first syntax, intersect returns a list containing one copy of each element found both in list-A and list-B.

In the second syntax, intersect returns a list of all elements in list-A that are also in list-B, without eliminating duplicates in list-A. bool is an expression evaluating to true or any other value not nil.

invert

syntax: (invert matrix [float-pivot])

Returns the inversion of a two-dimensional matrix in matrix. The matrix must be square, with the same number of rows and columns, and non-singular (invertible). Matrix inversion can be used to solve systems of linear equations (e.g., multiple regression in statistics). newLISP uses LU-decomposition of the matrix to find the inverse.

The dimensions of a matrix are defined by the number of rows times the number of elements in the first row. For missing elements in non-rectangular matrices, 0.0 (zero) is assumed. A matrix can either be a nested list or an array.

invert will return nil if the matrix is singular and cannot be inverted, and float-pivot is not specified.

irr

syntax: (irr list-amounts [list-times [num-guess]])

Calculates the internal rate of return of a cash flow per time period. The internal rate of return is the interest rate that makes the present value of a cash flow equal to 0.0 (zero). In-flowing (negative values) and out-flowing (positive values) amounts are specified in list-amounts. If no time periods are specified in list-times, amounts in list-amounts correspond to consecutive time periods increasing by 1 (1, 2, 3—). The algorithm used is iterative, with an initial guess of 0.5 (50 percent). Optionally, a different initial guess can be specified. The algorithm returns when a precision of 0.000001 (0.0001 percent) is reached. nil is returned if the algorithm cannot converge after 50 iterations.

If an initial investment of 1,000 yields 500 after the first year, 400 after two years, and so on, finally reaching 0.0 (zero) after five years, then that corresponds to a yearly return of about 20.2 percent. The next line demonstrates the relation between irr and npv. Only 9.9 percent returns are necessary when making the first withdrawal after three years.

In the last example, securities were initially purchased for 5,000, then for another 2,000 three months later. After a year, securities for 5,000 are sold. Selling the remaining securities after 18 months renders 6,000. The internal rate of return is 3.2 percent per month, or about 57 percent in 18 months.

json-error

syntax: (json-error)

When json-parse returns nil due to a failed JSON data translation, this function retrieves an error description and the last scan position of the parser.

json-parse

syntax: (json-parse str-json-data)

This function parses JSON formatted text and translates it to newLISP S-expressions. All data types conforming to the ECMA-262 standard are translated. The JSON values false and null will be represented by the symbols false and null in the symbolic newLISP expressions. Arrays in JSON will be represented by lists in newLISP. The resulting lists from JSON object data can be processed using assoc, lookup and ref.

For JSON attribute values not recognized or wrong JSON syntax, json-parse returns nil and json-error can be used to retrieve the error text.

Although most of the time JSON object types are parsed, all JSON data types can be parsed directly, without occurring as part of a JSON object. The following examples show parsing of a JSON array:

When the UTF-8 capable version of newLISP is used, JSON formatted Unicode gets translated into UTF-8:

The hex-code representation of Unicoder characters in JSON is the same as can be used in UTF-8 enabled newLISP.

Because JSON objects contain {,}," characters, quotes should not be used to limit JSON data, or all quotes inside the JSON data would need a preceding backslash \. {,} braces can be used as long as braces inside the JSON data are balanced. The safest delimiter are [text], [/text] tags — they suppress all special processing of the string when read by newLISP and are suitable to delimit large data sizes greater 2047 bytes.

join

syntax: (join list-of-strings [str-joint [bool-trail-joint]])

Concatenates the given list of strings in list-of-strings. If str-joint is present, it is inserted between each string in the join. If bool-trail-joint is true then a joint string is also appended to the last string.

See also the append, string, and explode functions, which are the inverse of the join operation.

kmeans-query

syntax: (kmeans-query list-data matrix-centroids)
syntax: (kmeans-query list-data matrix-data)

In the first usage, kmeans-query calculates the Euclidian distances from the data vector given in list-data to the centroids given in matrix-centroids. The data vector in list-data has m elements. The 2-dimensional list in matrix-centroids, result from a previous kmeans-train clustering, has k rows and m columns for k centroids measuring m features.

The data record (1 2 3) shows the smallest distance to the 3rd cluster centroid and would be classified as belonging to that cluster.

In the second application kmeans-query calculates Euclidian distances to a list of other data points which are not centroids. The following example calculates distances of the (1 2 3) data vector to all original points from the original kmeans-train data analysis.

We see that the smallest distances are shown for the data points in the 3rd cluster at offset 2.

If the numbers of elements - features - in records of list-data is different from the number of columns in the data or centroid matrix, then the smaller is taken for calculating the Euclidian distances. This is useful when the last column of the data matrix does not contain feature data, but labels identifying the cluster membership of a data point.

kmeans-train

syntax: (kmeans-train matrix-data int-k context [matrix-centroids])

The function performs Kmeans cluster analysis on matrix-data. All n data records in matrix-data are partitioned into a number of int-k different groups.

Both, the n * m matrix-data and the optional k * m matrix-centroids can be either nested lists or 2-dimensional arrays.

The Kmeans algorithm tries to minimize the sum of squared inner cluster distances (SSQ) from the cluster centroid. With each iteration the centroids get moved closer to their final position. On some data sets, the end result can depend on the starting centroid points. The right choice of initial centroids can speed up the process and avoid not wanted local minima.

When no optional matrix-centroids are given, kmeans-train will assign an initial random cluster membership to each data row and calculate starting centroids.

kmeans-train returns a vector of total SSQs, the sum of squared inner distances from the centroid inside the cluster for all clusters. The Iterating algorithm stops when the change of SSQ from one to the next iteration is less than 1e-10.

The following example analyses 20 data records measuring m = 3 features and tries to partition data into k = 3 clusters. Other numbers than k = 3 could be tried. The target is a result with few clusters of high density measured by the average inner cluster distances.

The returned list of SSQs shows how in each iteration the sum of inner squared distances decreases. The list in K:labels shows the membership fo each data point in the same order as in the data.

The centroids in K:centroids can be used for later classification of new data records using kmeans-query. When the number of clusters specified in int-k is too big, kmeans-train will produce unused centroids with nan or NaN data. When unused cluster centroids are present, the number in int-k should be reduced.

The average inner K:deviations from cluster members to their centroid show how dense a cluster is packed. Formally, deviations are calculated similarly to Euclidian distances and to standard deviations in conventional statistics. Squaring the deviations and multiplying each with their cluster size (number of members in the cluster) shows the inner SSQ of each cluster:

K:clusters gives indices of data records into the original data for each cluster. With these, individual clusters can be extracted from the data for further analysis:

The result context should be prefixed with MAIN when code is written in a namespace context. If the context does not exists already, it will be created.

Results in K:labels, K:clusters, K:centroids and K:deviations will be overwritten, if already present from previous runs of kmeans-train.

lambda

lambda-macro

lambda?

syntax: (lambda? exp)

Returns true only if the value of exp is a lambda expression; otherwise, returns nil.

last utf8

syntax: (last list)
syntax: (last array)
syntax: (last str)

In the second version the last character in the string str is returned as a string.

Note that last works on character boundaries rather than byte boundaries when the UTF-8–enabled version of newLISP is used. See also first, rest and nth.

last-error

syntax: (last-error)
syntax: (last-error int-error)

Reports the last error generated by newLISP due to syntax errors or exhaustion of some resource. For a summary of all possible errors see the chapter Error codes in the appendix.

If no error has occurred since the newLISP session was started, nil is returned.

When int-error is specified, a list of the number and the error text is returned.

For error numbers out of range the string "Unknown error" is given for the error text.

See also net-error for errors generated by networking conditions and sys-error for errors generated by the operating system.

legal?

syntax: (legal? str)

The token in str is verified as a legal newLISP symbol. Non-legal symbols can be created using the sym function (e.g. symbols containing spaces, quotes, or other characters not normally allowed). Non-legal symbols are created frequently when using them for associative data access:

The example shows that the string "one two" does not contain a legal symbol although a symbol can be created from this string and treated like a variable.

length bigint

syntax: (length exp)

Returns the number of elements in a list, the number of rows in an array and the number of bytes in a string or in a symbol name.

Applied to a number, length returns the number of digits for normal and big integers and the number of digits before the decimal separator for floats.

Before version 10.5.6 length returned the storage size in bytes for integers (4 or 8) and floats (8).

let

syntax: (let ((sym1 [exp-init1]) [(sym2 [exp-init2]) ... ]) body)
syntax: (let (sym1 exp-init1 [sym2 exp-init2 ... ]) body)

One or more variables sym1, sym2, ... are declared locally and initialized with expressions in exp-init1, exp-init2, etc. In the fully parenthesized first syntax, initializers are optional and assumed nil if missing.

When the local variables are initialized, the initializer expressions evaluate using symbol bindings as before the let statement. To incrementally use symbol bindings as evaluated during the initialization of locals in let, use letn.

One or more expressions in exp-body are evaluated using the local definitions of sym1, sym2 etc. let is useful for breaking up complex expressions by defining local variables close to the place where they are used. The second form omits the parentheses around the variable expression pairs but functions identically.

The variables x and y are initialized, then the expression (+ x y) is evaluated. The let form is just an optimized version and syntactic convenience for writing:

See also letn for an incremental or nested form of let and local for initializing to nil. See local for automatic initialization of variables to nil.

letex

syntax: (letex ((sym1 [exp-init1]) [(sym2 [exp-init2]) ... ]) body)
syntax: (letex (sym1 exp-init1 [sym2 exp-init2 ... ]) body)

This function combines let and expand to expand local variables into an expression before evaluating it. In the fully parenthesized first syntax initializers are optional and assumed nil if missing.

Both forms provide the same functionality, but in the second form the parentheses around the initializers can be omitted:

Before the expression '(x y z) gets evaluated, x, y and z are literally replaced with the initializers from the letex initializer list. The final expression which gets evaluated is '(1 2 3).

In the second example a function make-adder is defined for making adder functions:

letex evaluates n to the constant 3 and replaces c with it in the lambda expression. The second examples shows, how a letex variable can be expanded into itself.

letn

syntax: (letn ((sym1 [exp-init1]) [(sym2 [exp-init2]) ... ]) body)
syntax: (letn (sym1 exp-init1 [sym2 exp-init2 ... ]) body)

letn is like a nested let and works similarly to let, but will incrementally use the new symbol bindings when evaluating the initializer expressions as if several let were nested. In the fully parenthesized first syntax, initializers are optional and assumed nil if missing.

While in the first example using let the variable y is calculated using the binding of x before the let expression, in the second example using letn the variable y is calculated using the new local binding of x.

letn works like several nested let. The parentheses around the initializer expressions can be omitted.

list

syntax: (list exp-1 [exp-2 ... ])

The exp are evaluated and the values used to construct a new list. Note that arguments of array type are converted to lists.

list?

syntax: (list? exp)

Returns true only if the value of exp is a list; otherwise returns nil. Note that lambda and lambda-macro expressions are also recognized as special instances of a list expression.

load

syntax: (load str-file-name-1 [str-file-name-2 ... ] [sym-context])

Loads and translates newLISP from a source file specified in one or more str-file-name and evaluates the expressions contained in the file(s). When loading is successful, load returns the result of the last expression in the last file evaluated. If a file cannot be loaded, load throws an error.

An optional sym-context can be specified, which becomes the context of evaluation, unless such a context switch is already present in the file being loaded. By default, files which do not contain context switches will be loaded into the MAIN context.

The str-file-name specs can contain URLs. Both http:// and file:// URLs are supported.

In case expressions evaluated during the load are changing the context, this will not influence the programming module doing the load.

The current context after the load statement will always be the same as before the load.

load with HTTP URLs can also be used to load code remotely from newLISP server nodes running on a Unix-like operating system. In this mode, load will issue an HTTP GET request to the target URL. Note that a double backslash is required when path names are specified relative to the root directory. load in HTTP mode will observe a 60-second timeout.

The second to last line causes the files to be loaded into the context MyCTX. The quote forces the context to be created if it did not exist.

local

syntax: (local (sym-1 [sym-2 ... ]) body)

Initializes one or more symbols in sym-1— to nil, evaluates the expressions in body, and returns the result of the last evaluation.

local works similarly to let, but local variables are all initialized to nil.

local provides a simple way to localize variables without explicit initialization.

log

syntax: (log num)
syntax: (log num num-base)

In the first syntax, the expression in num is evaluated and the natural logarithmic function is calculated from the result.

lookup

syntax: (lookup exp-key list-assoc [int-index [exp-default]])

Finds in list-assoc an association, the key element of which has the same value as exp-key, and returns the int-index element of association (or the last element if int-index is absent).

Optionally, exp-default can be specified, which is returned if an association matching exp-key cannot be found. If the exp-default is absent and no association has been found, nil is returned.

lookup is similar to assoc but goes one step further by extracting a specific element found in the list.

lower-case utf8

syntax: (lower-case str)

Converts the characters of the string in str to lowercase. A new string is created, and the original is left unaltered.

macro

syntax: (macro (sym-name [sym-param-1 ... ]) [body-1 ... ])

The macro function is used to define expansion macros. The syntax of macro is identical to the syntax of define-macro. But while define-macro defines are fexprs functions to be evaluated at run-time, macro defines a function to be used during the source loading and reading process to transform certain expression call patterns into different call patterns.

Internally all macro defined symbol call patterns are translated using the expand expression during source reading. This can be shown using the read-expr function:

All variable names to be expanded must start in upper-case. Macros can be nested containing other macros defined earlier. But macro definitions cannot be repeated for the same symbol during the same newLISP session. To redefine a macro, e.g. for reading source with a different definition of an exisiting macro definition, use the constant function in the following way:

Note, that constant can be used only to re-define macros, not to create new macros. Internally newLISP knows that macro defined symbols are executed during source reading, not evaluation.

The redefinition will only affect future read code, it will not affect code already load and translated by the reader routines.

Using map and apply with macro

This is useful to find out how the expansion mechanism of our macro definition works during source load time.

Differences between macro and define-macro and potential problems.

macro definitions are not susceptible to variable capture as are fexprs made with define-macro:

But expansion macros using macro are susceptible to unwanted double evaluation, just like define-macro is:

In both cases the incoming expression (inc a) gets evaulated twice. This must be considered when writing both, macro or define-macro expressions and symbols occur more than once in the body of the definition.

macro?

syntax: (macro? exp)

Returns true if exp evaluates to a lambda-macro expression. If exp evaluates to a symbol and the symbol contains a macro-expansion expression made with the macro function, true is also returned. In all other cases nil is returned.

main-args

syntax: (main-args)
syntax: (main-args int-index)

main-args returns a list with several string members, one for program invocation and one for each of the command-line arguments.

After newlisp 1 2 3 is executed at the command prompt, main-args returns a list containing the name of the invoking program and three command-line arguments.

Optionally, main-args can take an int-index for indexing into the list. Note that an index out of range will cause nil to be returned, not the last element of the list like in list-indexing.

Note that when newLISP is executed from a script, main-args also returns the name of the script as the second argument:

make-dir

syntax: (make-dir str-dir-name [int-mode])

Creates a directory as specified in str-dir-name, with the optional access mode int-mode. Returns true or nil depending on the outcome. If no access mode is specified, most Unix systems default to drwxr-xr-x.

On Unix systems, the access mode specified will also be masked by the OS's user-mask set by the system administrator. The user-mask can be retrieved on Unix systems using the command umask and is usually 0022 (octal), which masks write (and creation) permission for non-owners of the file.

This example creates a directory named adir in the current directory with an access mode of 0750 (octal 750 = drwxr-x---).

map

syntax: (map exp-functor list-args-1 [list-args-2 ... ])

Successively applies the primitive function, defined function, or lambda expression exp-functor to the arguments specified in list-args-1 list-args-2—, returning all results in a list. Since version 10.5.5 list-args can also be array vectors, but the returned result will always be a list.

Note that the quote before the operand can be omitted because primitives evaluate to themselves in newLISP.

The number of arguments used is determined by the length of the first argument list. Arguments missing in other argument lists cause map to stop collecting parameters for that level of arguments. This ensures that the nth parameter list gets converted to the nth column during the transposition occurring. If an argument list contains too many elements, the extra ones will be ignored.

mat

syntax: (mat + | - | * | / matrix-A matrix-B)
syntax: (mat + | - | * | / matrix-A number)

Using the first syntax, this function performs fast floating point scalar operations on two-dimensional matrices in matrix-A or matrix-B. The type of operation is specified by one of the four arithmetic operators +, -, *, or /. This type of arithmetic operator is typically used for integer operations in newLISP. In the case of mat, however, all operations will be performed as floating point operations (add, sub, mul, div).

Matrices in newLISP are two-dimensional lists or arrays. Internally, newLISP translates lists and arrays into fast, accessible C-language data objects. This makes matrix operations in newLISP as fast as those coded directly in C. The same is true for the matrix operations multiply and invert.

Using the second syntax, all cells in matrix-A are operated on with a scalar in number:

match

syntax: (match list-pattern list-match [bool])

The pattern in list-pattern is matched against the list in list-match, and the matching expressions are returned in a list. The three wildcard characters ?, +, and * can be used in list-pattern.

Wildcard characters may be nested. match returns a list of matched expressions. For each ? (question mark), a matching expression element is returned. For each + (plus sign) or * (asterisk), a list containing the matched elements is returned. If the pattern cannot be matched against the list in list-match, match returns nil. If no wildcard characters are present in the pattern an empty list is returned.

Optionally, the Boolean value true (or any other expression not evaluating to nil) can be supplied as a third argument. This causes match to show all elements in the returned result.

match is frequently employed as a functor parameter in find, ref, ref-all and replace and is internally used by find-all for lists.

Note that the * operator tries to grab the fewest number of elements possible, but match backtracks and grabs more elements if a match cannot be found.

The + operator works similarly to the * operator, but it requires at least one list element.

The following example shows how the matched expressions can be bound to variables.

Note that match for strings has been eliminated. For more powerful string matching, use regex, find, find-all or parse.

max

syntax: (max num-1 [num-2 ... ])

member

syntax: (member exp list)
syntax: (member str-key str [num-option])

In the first syntax, member searches for the element exp in the list list. If the element is a member of the list, a new list starting with the element found and the rest of the original list is constructed and returned. If nothing is found, nil is returned. When specifying num-option, member performs a regular expression search.

In the second syntax, member searches for str-key in str. If str-key is found, all of str (starting with str-key) is returned. nil is returned if nothing is found.

min

syntax: (min num-1 [num-2 ... ])

mod

syntax: (mod num-1 num-2 [num-3 ... ])
syntax: (mod num-1)

Calculates the modular value of the numbers in num-1 and num-2. mod computes the remainder from the division of the numerator num-i by the denominator num-i + 1. Specifically, the return value is numerator - n * denominator, where n is the quotient of the numerator divided by the denominator, rounded towards zero to an integer. The result has the same sign as the numerator and its magnitude is less than the magnitude of the denominator.

In the second syntax 1 is assumed for num-2 and the result is the fractional part of num-1.

mul

syntax: (mul num-1 num-2 [num-3 ... ])

Evaluates all expressions num-1—, calculating and returning the product. mul can perform mixed-type arithmetic, but it always returns floating point numbers. Any floating point calculation with NaN also returns NaN.

multiply

syntax: (multiply matrix-A matrix-B)

Returns the matrix multiplication of matrices in matrix-A and matrix-B. If matrix-A has the dimensions n by m and matrix-B the dimensions k by l (m and k must be equal), the result is an n by l matrix. multiply can perform mixed-type arithmetic, but the results are always double precision floating points, even if all input values are integers.

The dimensions of a matrix are determined by the number of rows and the number of elements in the first row. For missing elements in non-rectangular matrices, 0.0 is assumed. A matrix can either be a nested list or array.

When multiplying a matrix with a vector of n elements, the vector must be transformed into n rows by 1 column matrix using transpose.

name

NaN?

syntax: (NaN? float)

Tests if the result of a floating point math operation is a NaN. Certain floating point operations return a special IEEE 754 number format called a NaN for 'Not a Number'.

Note that all floating point arithmetic operations with a NaN yield a NaN. All comparisons with NaN return nil, but true when comparing to itself. Comparison with itself, however, would result in not true when using ANSI C. Integer operations treat NaN as 0 (zero) values.

net-accept

syntax: (net-accept int-socket)

Accepts a connection on a socket previously put into listening mode. Returns a newly created socket handle for receiving and sending data on this connection.

Note that for ports less than 1024, newLISP must be started in superuser mode on Unix-like operating systems.

See also the files server and client examples in the examples/ directory of the source distribution.

net-close

syntax: (net-close int-socket [true])

Closes a network socket in int-socket that was previously created by a net-connect or net-accept function. Returns true on success and nil on failure.

The optional true flag suppresses immediate shutdown of sockets by waiting for pending data transmissions to finish.

net-connect

syntax: (net-connect str-remote-host int-port [int-timeout-ms])
syntax: (net-connect str-remote-host int-port [str-mode [int-ttl]])
syntax: (net-connect str-file-path)

In the first syntax, connects to a remote host computer specified in str-remote-host and a port specified in int-port. Returns a socket handle after having connected successfully; otherwise, returns nil.

If successful, the net-connect function returns a socket number which can be used to send and receive information from the host. In the example a HTTP GET request is sent and subsequently a web page received. Note that newLISP has already a built-in function get-url offering the same functionality.

Optionally a timeout value int-timeout in milliseconds can be specified. Without a timeout value the function will wait up to 10 seconds for an open port. With a timeout value the function can be made to return on an unavailable port much earlier or later. The following example shows a port scanner looking for open ports:

The programs takes the host string from the shell command line as either a domain name or an IP number in dot notation then tries to open each port from 1 to 1024. For each open port the port number and the service description string is printed. If no description is available, an empty string "" is output. For closed ports the function outputs numbers in the shell window staying on the same line.

On Unix net-connect may return with nil before the timeout expires, when the port is not available. On MS Windows net-connect will always wait for the timeout to expire before failing with nil.

UDP communications

In the second syntax, a third parameter, the string "udp" or "u" can be specified in the optional str-mode to create a socket suited for UDP (User Datagram Protocol) communications. In UDP mode, net-connect does not try to connect to the remote host, but creates the socket and binds it to the remote address, if an address is specified. A subsequent net-send will send a UDP packet containing that target address. When using net-send-to, only one of the two functions net-connect or net-send-to should provide a target address. The other function should specify and empty string "" as the target address.

The functions net-receive and net-receive-from can both be used and will perform UDP communications when the "udp" option as been used in net-listen or net-connect. net-select and net-peek can be used to check for received data in a non-blocking fashion.

net-listen binds a specific local address and port to the socket. When net-connect is used, the local address and port will be picked by the socket-stack functions of the host OS.

UDP multicast communications

When specifying "multi" or "m" as a third parameter for str-mode, a socket for UDP multicast communications will be created. Optionally, the fourth parameter int-ttl can be specified as a TTL (time to live) value. If no int-ttl value is specified, a value of 3 is assumed.

Note that specifying UDP multicast mode in net-connect does not actually establish a connection to the target multicast address but only puts the socket into UDP multicasting mode. On the receiving side, use net-listen together with the UDP multicast option.

On the server side, net-peek or net-select can be used for non-blocking communications. In the above example, the server would block until a datagram is received.

The address 226.0.0.1 is just one multicast address in the Class D range of multicast addresses from 224.0.0.0 to 239.255.255.255.

UDP broadcast communications

Specifying the string "broadcast" or "b" in the third parameter, str-mode, causes UDP broadcast communications to be set up. In this case, the broadcast address ending in 255 is used.

Note that on the receiving side, net-listen should be used with the default address specified with an "" (empty string). Broadcasts will not be received when specifying an address. As with all UDP communications, net-listen does not actually put the receiving side in listen mode, but rather sets up the sockets for the specific UDP mode.

The net-select or net-peek functions can be used to check for incoming communications in a non-blocking fashion.

Local domain Unix sockets

In the third syntax, net-connect connects to a server on the local file system via a local domain Unix socket named using str-file-path. Returns a socket handle after having connected successfully; otherwise, returns nil.

A local domain file system socket is created and returned. On the server side, local domain sockets have been created using net-listen and net-accept. After the connection has been established the functions net-select, net-send and net-receive can be used as usual for TCP/IP stream communications. This type of connection can be used as a fast bi-directional communications channel between processes on the same file system. This type of connection is not available on MS Windows platforms.

net-error

syntax: (net-error)
syntax: (net-error int-error)

Functions that communicate using sockets close the socket automatically and remove it from the net-sessions list.

no	description
1	Cannot open socket
2	DNS resolution failed
3	Not a valid service
4	Connection failed
5	Accept failed
6	Connection closed
7	Connection broken
8	Socket send() failed
9	Socket recv() failed
10	Cannot bind socket
11	Too many sockets in net-select
12	Listen failed
13	Badly formed IP
14	Select failed
15	Peek failed
16	Not a valid socket
17	Cannot unblock socket
18	Operation timed out
19	HTTP bad formed URL
20	HTTP file operation failed
21	HTTP transfer failed
22	HTTP invalid response from server
23	HTTP no response from server
24	HTTP no content
25	HTTP error in header
26	HTTP error in chunked format

When int-error is specified the number and error text for that error number is returned.

net-eval

syntax: (net-eval str-host int-port exp [int-timeout [func-handler]])
syntax: (net-eval '((str-host int-port exp) ... ) [int-timeout [func-handler]])

Can be used to evaluate source remotely on one or more newLISP servers. This function handles all communications necessary to connect to the remote servers, send source for evaluation, and wait and collect responses.

The expression in exp will be evaluated remotely in the environment of the target node. The exp is either a quoted expression, or it is enclosed in string delimiters. For bigger expressions [text] ... [/text] delimiters can be used instead of double quotes " ... ". Only one expression should be enclosed in the string. When more than one are specified, all will get evaluated in the target node, but only the result of the first will be returned.

The -d daemon mode allows newLISP to maintain state between connections. When keeping state between connections is not desired, the inetd daemon mode offers more advantages. The Internet inetd or xinetd services daemon will start a new newLISP process for each client connection. This makes for much faster servicing of multiple connections. In -d daemon mode, each new client request would have to wait for the previous request to be finished. See the chapter inetd daemon mode on how to configure this mode correctly.

Instead of 4711, any other port number can be used. Multiple nodes can be started on different hosts and with the same or different port numbers. The -l or -L logging options can be specified to log connections and remote commands.

In the first syntax, net-eval talks to only one remote newLISP server node, sending the host in str-host on port int-port a request to evaluate the expression exp. If int-timeout is not given, net-eval will wait up to 60 seconds for a response after a connection is made. Otherwise, if the timeout in milliseconds has expired, nil is returned; else, the evaluation result of exp is returned.

The second syntax of net-eval returns a list of the results after all of the responses are collected or timeout occurs. Responses that time out return nil. The last example line shows how to specify a local-domain Unix socket specifying the socket path and a port number of 0. Connection errors or errors that occur when sending information to nodes are returned as a list of error numbers and descriptive error strings. See the function net-error for a list of potential error messages.

The first example shows two expressions evaluated on two different remote nodes. In the second example, both nodes run on the local computer. This may be useful when debugging or taking advantage of multiple CPUs on the same computer. When specifying 0 for the port number , net-eval takes the host name as the file path to the local-domain Unix socket.

Note that definitions of foo and myfunc must both exist in the target environment. This can be done using a net-eval sending define statements before. It also can be done by preloading code when starting remote nodes.

When nodes are inetd or xinetd-controlled, several nodes may have the same IP address and port number. In this case, the Unix daemon inetd or xinetd will start multiple newLISP servers on demand. This is useful when testing distributed programs on just one machine. The last example illustrates this case. It is also useful on multi core CPUs, where the platform OS can distribute different processes on to different CPU cores.

The source sent for evaluation can consist of entire multiline programs. This way, remote nodes can be loaded with programs first, then specific functions can be called. For large program files, the functions put-url or save (with a URL file name) can be used to transfer programs. The a net-eval statement could load these programs.

Optionally, a handler function can be specified. This function will be repeatedly called while waiting and once for every remote evaluation completion.

The example shows how the list of node specs can be assembled from a list of nodes and sources to evaluate. This may be useful when connecting to a larger number of remote nodes.

While waiting for input from remote hosts, myhandler will be called with nil as the argument to param. When a remote node result is completely received, myhandler will be called with param set to a list containing the remote host name or IP number, the port, and the resulting expression. net-eval will return true before a timeout or nil if the timeout was reached or exceeded. All remote hosts that exceeded the timeout limit will contain a nil in their results list.

For a longer example see this program: mapreduce. The example shows how a word counting task gets distributed to three remote nodes. The three nodes count words in different texts and the master node receives and consolidates the results.

net-interface

syntax: (net-interface str-ip-addr)
syntax: (net-interface)

Sets the default local interface address to be used for network connections. If not set then network functions will default to an internal default address, except when overwritten by an optional interface address given in net-listen.

When no str-ip-addr is specified, the current default is returned. If the net-interface has not been used yet to specify an IP address, the address 0.0.0.0 is returned. This means that all network routines will use the default address preconfigured by the underlying operating system.

This function has only usage on multihomed servers with either multiple network interface hardware or otherwise supplied multiple IP numbers. On all other machines network functions will automatically select the single network interface installed.

On error the function returns nil and net-error can be used to report the error.

An interface address can be defined as either an IP address or a name. The return value is the address given in str-ip-addr

net-ipv

syntax: (net-ipv int-version)
syntax: (net-ipv)

Switches between IPv4 and IPv6 internet protocol versions. int-version contains either a 4 for IPv4 or a 6 for IPv6. When no parameter is given, net-ipv returns the current setting.

By default newLISP starts up in IPv4 mode. The IPv6 protocol mode can also be specified from the commandline when starting newlisp:

Once a socket is connected with either net-connect or listened on with net-listen, the net-accept, net-select, net-send, net-receive and net-receive-from functions automatically adjust to the address protocol used when creating the sockets. Different connections with different IPv4/6 settings can be open at the same time.

Note, that currently net-packet does not support IPv6 and will work in IPv4 mode regardless of settings.

net-listen

syntax: (net-listen int-port [str-ip-addr [str-mode]])
syntax: (net-listen str-file-path)

Listens on a port specified in int-port. A call to net-listen returns immediately with a socket number, which is then used by the blocking net-accept function to wait for a connection. As soon as a connection is accepted, net-accept returns a socket number that can be used to communicate with the connecting client.

The example waits for a connection on port 1234, then reads incoming lines until an empty line is received. Note that listening on ports lower than 1024 may require superuser access on Unix systems.

On computers with more than one interface card, specifying an optional interface IP address or name in str-ip-addr directs net-listen to listen on the specified address.

Local domain Unix sockets

In the second syntax, net-listen listens for a client on the local file system via a local domain Unix socket named using str-file-path. If successful, returns a socket handle that can be used with net-accept to accept a client connection; otherwise, returns nil.

A local domain file system socket is created and listened on. A client will try to connect using the same str-file-path. After a connection has been accepted the functions net-select, net-send and net-receive can be used as usual for TCP/IP stream communications. This type of connection can be used as a fast bi-directional communications channel between processes on the same file system. This type of connection is not available on MS Windows platforms.

UDP communications

As a third parameter, the optional string "udp" or "u" can be specified in str-mode to create a socket suited for UDP (User Datagram Protocol) communications. A socket created in this way can be used directly with net-receive-from to await incoming UDP data without using net-accept, which is only used in TCP communications. The net-receive-from call will block until a UDP data packet is received. Alternatively, net-select or net-peek can be used to check for ready data in a non-blocking fashion. To send data back to the address and port received with net-receive-from, use net-send-to.

Note that net-peer will not work, as UDP communications do not maintain a connected socket with address information.

The first example listens on a specific network adapter, while the second example listens on the default adapter. Both calls return a socket number that can be used in subsequent net-receive, net-receive-from, net-send-to, net-select, or net-peek function calls.

Both a UDP server and UDP client can be set up using net-listen with the "udp" option. In this mode, net-listen does not really listen as in TCP/IP communications; it just binds the socket to the local interface address and port.

For a working example, see the files examples/client and examples/server in the newLISP source distribution.

Instead of net-listen and the "udp" option, the functions net-receive-udp and net-send-udp can be used for short transactions consisting only of one data packet.

net-listen, net-select, and net-peek can be used to facilitate non-blocking reading. The listening/reading socket is not closed but is used again for subsequent reads. In contrast, when the net-receive-udp and net-send-udp pair is used, both sides close the sockets after sending and receiving.

UDP multicast communications

If the optional string str-mode is specified as "multi" or "m", net-listen returns a socket suitable for multicasting. In this case, str-ip-addr contains one of the multicast addresses in the range 224.0.0.0 to 239.255.255.255. net-listen will register str-ip-addr as an address on which to receive multicast transmissions. This address should not be confused with the IP address of the server host.

On the server side, net-peek or net-select can be used for non-blocking communications. In the example above, the server would block until a datagram is received.

Packet divert sockets and ports

If str-mode is specified as "divert" or "d", a divert socket can be created for a divert port in int-port on BSD like platforms. The content of IP address in str-ip-addr is ignored and can be specified as an empty string. Only the int-port is relevant and will be bound to the raw socket returned.

To use the divert option in net-listen, newLISP must run in super-user mode. This option is only available on Unix like platforms.

The divert socket will receive all raw packets diverted to the divert port. Packets may also be written back to a divert socket, in which case they re-enter OS kernel IP packet processing.

Rules for packet diversion to the divert port must be defined using either the ipfw BSD or ipchains Linux configuration utilities.

The net-receive-from and net-send-to functions are used to read and write raw packets on the divert socket created and returned by the net-listen statement. The same address received by net-receive-from is used in the net-send-to call when re-injecting the packet:

For more information see the Unix man pages for divert and the ipfw (BSDs) or ipchains (Linux) configuration utilities.

net-local

syntax: (net-local int-socket)

Returns the IP number and port of the local computer for a connection on a specific int-socket.

net-lookup

syntax: (net-lookup str-ip-number)
syntax: (net-lookup str-hostname [bool])

Returns either a hostname string from str-ip-number in IP dot format or the IP number in dot format from str-hostname:

Optionally, a bool flag can be specified in the second syntax. If the expression in bool evaluates to anything other than nil, host-by-name lookup will be forced, even if the name string starts with an IP number.

net-packet

syntax: (net-packet str-packet)

The function allows custom configured network packets to be sent via a raw sockets interface. The packet in str-packet must start with an IP (Internet Protocol) header followed by either a TCP, UDP or ICMP header and optional data. newLISP must be run with super user privileges, and this function is only available on Mac OS X, Linux and other Unix operating systems and only for IPv4. Currently net-packet is IPv4 only and has been tested on Mac OS X, Linux and OpenBSD.

On success the function returns the number of bytes sent. On failure the function returns nil and both, net-error and sys-error, should be inspected.

When custom configured packets contain zeros in the checksum fields, net-packet will calculate and insert the correct checksums. Already existing checksums stay untouched.

The following example injects a UDP packet for IP number 192.168.1.92. The IP header consists of 20 bytes ending with the target IP number. The following UDP header has a length of 8 bytes and is followed by the data string Hello World. The checksum bytes in both headers are left as 0x00 0x00 and will be recalculated internally.

The net-packet function is used when testing net security. Its wrong application can upset the correct functioning of network routers and other devices connected to a network. For this reason the function should only be used on well isolated, private intra-nets and only by network professionals.

For other examples of packet configuration, see the file qa-specific-tests/qa-packet in the newLISP source distribution.

net-peek

syntax: (net-peek int-socket)

Returns the number of bytes ready for reading on the network socket int-socket. If an error occurs or the connection is closed, nil is returned.

net-peer

syntax: (net-peer int-socket)

Returns the IP number and port number of the remote computer for a connection on int-socket.

Use the net-local function to access the local computer's IP number and port number.

net-ping

syntax: (net-ping str-address [int-timeout [int-count bool]]])
syntax: (net-ping list-addresses [int-timeout [int-count bool]]])

This function is only available on Unix-based systems and must be run in superuser mode, i.e. using: sudo newlisp to start newLISP on Mac OS X or other BSD's, or as the root user on Linux. Broadcast mode and specifying ranges with the - (hyphen) or * (star) are not available on IPv6 address mode.

In the first syntax, net-ping sends a ping ICMP 64-byte echo request to the address specified in str-address. If it is a broadcast address, the ICMP packet will be received by all addresses on the subnet. Note that for security reasons, many computers do not answer ICMP broadcast ping (ICMP_ECHO) requests. An optional timeout parameter can be specified in int-timeout. If no timeout is specified, a waiting time of 1000 milliseconds (one second) is assumed.

net-ping returns either a list of lists of IP strings and round-trip time in microseconds for which a response was received or an empty list if no response was received.

A return value of nil indicates a failure. Use the net-error function to retrieve the error message. If the message reads Cannot open socket, it is probably because newLISP is running without root permissions. newLISP can be started using:

Alternatively, newLISP can be installed with the set-user-ID bit set to run in superuser mode.

In the second syntax, net-ping is run in batch mode. Only one socket is opened in this mode, but multiple ICMP packets are sent out—one each to multiple addresses specified in a list or specified by range. Packets are sent out as fast as possible. In this case, multiple answers can be received. If the same address is specified multiple times, the receiving IP address will be flooded with ICMP packets.

To limit the number of responses to be waited for in broadcast or batch mode, an additional argument indicating the maximum number of responses to receive can be specified in int-count. Usage of this parameter can cause the function to return sooner than the specified timeout. When a given number of responses has been received, net-ping will return before the timeout has occurred. Not specifying int-count or specifying 0 assumes an int-count equal to the number of packets sent out.

As third optional parameter, a true value can be specified. This setting will return an error string instead of the response time, if the host does not answer.

Broadcast or batch mode—as well as normal addresses and IP numbers or hostnames— can be mixed in one net-ping statement by putting all of the IP specs into a list.

The second and third lines show how the batch mode of net-ping can be initiated by specifying the * (asterisk) as a wildcard character for the last subnet octet in the IP number. The fourth and fifth lines show how an IP range can be specified for the last subnet octet in the IP number. net-ping will iterate through all numbers from either 1 to 254 for the star * or the range specified, sending an ICMP packet to each address. Note that this is different from the broadcast mode specified with an IP octet of 255. While in broadcast mode, net-ping sends out only one packet, which is received by multiple addresses. Batch mode explicitly generates multiple packets, one for each target address. When specifying broadcast mode, int-count should be specified, too.

When sending larger lists of IPs in batch mode over one socket, a longer timeout may be necessary to allow enough time for all of the packets to be sent out over one socket. If the timeout is too short, the function net-ping may return an incomplete list or the empty list (). In this case, net-error will return a timeout error. On error, nil is returned and net-error can be used to retrieve an error message.

On some systems only lists up to a specific length can be handled regardless of the timeout specified. In this case, the range should be broken up into sub-ranges and used with multiple net-ping invocations. In any case, net-ping will send out packages as quickly as possible.

net-receive !

syntax: (net-receive int-socket sym-buffer int-max-bytes [wait-string])

Receives data on the socket int-socket into a string contained in sym-buffer. sym-buffer can also be a default functor specified by a context symbol for reference passing in and out of user-defined functions.

A maximum of int-max-bytes is received. net-receive returns the number of bytes read. If there is a break in the connection, nil is returned. The space reserved in sym-buffer is exactly the size of bytes read.

Note that net-receive is a blocking call and does not return until the data arrives at int-socket. Use net-peek or net-select to find out if a socket is ready for reading.

Optionally, a wait-string can be specified as a fourth parameter. net-receive then returns after a character or string of characters matching wait-string is received. The wait-string will be part of the data contained in sym-buffer.

When calling gettime, the program connects to port 13 of the server netcom.com. Port 13 is a date-time service on most server installations. Upon connection, the server sends a string containing the date and time of day.

The second example defines a new function net-receive-line, which returns after receiving a newline character (a string containing one character in this example) or 256 characters. The "\n" string is part of the contents of sBuff.

Note that when the fourth parameter is specified, net-receive is slower than the normal version because information is read character-by-character. In most situations, the speed difference can be neglected.

net-receive-from

syntax: (net-receive-from int-socket int-max-size)

net-receive-from can be used to set up non-blocking UDP communications. The socket in int-socket must previously have been opened by either net-listen or net-connect (both using the "udp" option). int-max-size specifies the maximum number of bytes that will be received. On Linux/BSD, if more bytes are received, those will be discarded; on MS Windows, net-receive-from returns nil and closes the socket.

On success net-receive returns a list of the data string, remote IP number and remote port used. On failure it returns nil.

The second line in this example is optional. Without it, the net-receive-from call would block until data arrives. A UDP server could be set up by listening and polling several ports, serving them as they receive data.

Both, the sender and the receiver have to issue net-listen commands for UDP mode. Not for listening as in TCP/IP protocol communications, but to create the socket bound to the port and address. For a complete example see the files udp-server.lsp and udp-client.lsp in the newlisp-x.x.x/examples/ directory of the source distribution.

Note that net-receive could not be used in this case because it does not return the sender's address and port information, which are required to talk back. In UDP communications, the data packet itself contains the address of the sender, not the socket over which communication takes place. net-receive can also be used for TCP/IP communications.

See also the net-connect function with the "udp" option and the net-send-to function for sending UDP data packets over open connections.

net-receive-udp

syntax: (net-receive-udp int-port int-maxsize [int-microsec [str-addr-if]])

Receives a User Datagram Protocol (UDP) packet on port int-port, reading int-maxsize bytes. If more than int-maxsize bytes are received, bytes over int-maxsize are discarded on Linux/BSD; on MS Windows, net-receive-udp returns nil. net-receive-udp blocks until a datagram arrives or the optional timeout value in int-microsec expires. When setting up communications between datagram sender and receiver, the net-receive-udp statement must be set up first.

net-receive-udp returns a list containing a string of the UDP packet followed by a string containing the sender's IP number and the port used.

See also the net-send-udp function for sending datagrams and the pack and unpack functions for packing and unpacking binary information.

To listen on a specified address on computers with more than one interface card, an interface IP address or name can be optionally specified in str-addr-if. When specifying str-addr-if, a timeout must also be specified in int-wait.

As an alternative, UDP communication can be set up using net-listen, or net-connect together with the "udp" option to make non-blocking data exchange possible with net-receive-from and net-send-to.

net-select

syntax: (net-select int-socket str-mode int-micro-seconds)
syntax: (net-select list-sockets str-mode int-micro-seconds)

In the first form, net-select finds out about the status of one socket specified in int-socket. Depending on str-mode, the socket can be checked if it is ready for reading or writing, or if the socket has an error condition. A timeout value is specified in int-micro-seconds.

In the second syntax, net-select can check for a list of sockets in list-sockets.

Read, send, or accept operations can be handled without blocking by using the net-select function. net-select waits for a socket to be ready for the value given in int-micro-seconds, then returns true or nil depending on the readiness of the socket. During the select loop, other portions of the program can run. On error, net-error is set. When -1 is specified for int-micro-seconds, net-select will never time out.

When net-select is used, several listen and connection sockets can be watched, and multiple connections can be handled. When used with a list of sockets, net-select will return a list of ready sockets. The following example would listen on two sockets and continue accepting and servicing connections:

In the second syntax, a list is returned containing all the sockets that passed the test; if timeout occurred, an empty list is returned. An error causes net-error to be set.

Note that supplying a nonexistent socket to net-select will cause an error to be set in net-error.

net-send

syntax: (net-send int-socket str-buffer [int-num-bytes])

Sends the contents of str-buffer on the connection specified by int-socket. If int-num-bytes is specified, up to int-num-bytes are sent. If int-num-bytes is not specified, the entire contents will be sent. net-send returns the number of bytes sent or nil on failure.

The first net-send sends the string "hello there", while the second net-send sends only the string "hello".

net-send-to

syntax: (net-send-to str-remotehost int-remoteport str-buffer int-socket)

Can be used for either UDP or TCP/IP communications. The socket in int-socket must have previously been opened with a net-connect or net-listen function. If the opening functions was used with the "udp" option, net-listen or net-connect are not used to listen or to connect but only to create the UDP socket. The host in str-remotehost can be specified either as a hostname or as an IP-number string.

When using net-connect together with net-send-to, then only one of the functions should specify the remote host. The other should leave the address as an empty string.

In the examples both, the client and the server use net-listen to create the UDP socket for sending and receiving. The server extracts the client address and port from the message received and uses it in the net-send-to statement.

net-send-udp

syntax: (net-send-udp str-remotehost int-remoteport str-buffer [bool])

Sends a User Datagram Protocol (UDP) to the host specified in str-remotehost and to the port in int-remoteport. The data sent is in str-buffer.

The theoretical maximum data size of a UDP packet on an IPv4 system is 64K minus IP layer overhead, but much smaller on most Unix flavors. 8k seems to be a safe size on Mac OS X, BSDs and Linux.

No previous setup using net-connect or net-listen is necessary. net-send-udp returns immediately with the number of bytes sent and closes the socket used. If no net-receive-udp statement is waiting at the receiving side, the datagram sent is lost. When using datagram communications over insecure connections, setting up a simple protocol between sender and receiver is recommended for ensuring delivery. UDP communication by itself does not guarantee reliable delivery as TCP/IP does.

net-send-udp is also suitable for sending binary information (e.g., the zero character or other non-visible bytes). For a more comprehensive example, see net-receive-udp.

Optionally, the sending socket can be put in broadcast mode by specifying true or any expression not evaluating to nil in bool:

The UDP will be sent to all nodes on the 192.168.1 network. Note that on some operating systems, sending the network mask 255 without the bool true option will enable broadcast mode.

As an alternative, the net-connect function using the "udp" option—together with the net-send-to function—can be used to talk to a UDP listener in a non-blocking fashion.

net-service

syntax: (net-service str-service str-protocol)
syntax: (net-service int-port str-protocol)

In the first syntax net-service makes a lookup in the services database and returns the standard port number for this service.

In the second syntax a service port is supplied in int-port to look up the service name.

net-sessions

syntax: (net-sessions)

new

syntax: (new context-source sym-context-target [bool])
syntax: (new context-source)

The context context-source is copied to sym-context-target. If the target context does not exist, a new context with the same variable names and user-defined functions as in context-source is created. If the target context already exists, then new symbols and definitions are added. Existing symbols are only overwritten when the expression in bool evaluates to anything other than nil; otherwise, the content of existing symbols will remain. This makes mixins of context objects possible. new returns the target context, which cannot be MAIN.

In the second syntax, the existing context in context-source gets copied into the current context as the target context.

All references to symbols in the originating context will be translated to references in the target context. This way, all functions and data structures referring to symbols in the original context will now refer to symbols in the target context.

The first line in the example creates a new context called CTX-2 that has the exact same structure as the original one. Note that CTX is not quoted because contexts evaluate to themselves, but CTX-2 must be quoted because it does not exist yet.

The second line merges the context CTX into MyCTX. Any existing symbols of the same name in MyCTX will be overwritten. Because MyCTX already exists, the quote before the context symbol can be omitted.

Context symbols need not be mentioned explicitly, but they can be contained in variables:

The example refers to contexts in variables and merges context foo into bar.

See also the function def-new for moving and merging single functions instead of entire contexts. See the context function for a more comprehensive example of new.

nil?

syntax: (nil? exp)

If the expression in exp evaluates to nil, then nil? returns true; otherwise, it returns nil.

The nil? predicate is useful for distinguishing between nil and the empty list ().

Note that nil? means strictly nil while true? means everything not nil or the empty list ().

normal

syntax: (normal float-mean float-stdev int-n)
syntax: (normal float-mean float-stdev)

In the first form, normal returns a list of length int-n of random, continuously distributed floating point numbers with a mean of float-mean and a standard deviation of float-stdev. The random generator used internally can be seeded using the seed function.

In the second form, normal returns a single normal distributed floating point number:

When no parameters are given, normal assumes a mean of 0.0 and a standard deviation of 1.0.

See also the random and rand functions for evenly distributed numbers, amb for randomizing evaluation in a list of expressions, and seed for setting a different start point for pseudo random number generation.

not

syntax: (not exp)

If exp evaluates to nil or the empty list (), then true is returned; otherwise, nil is returned.

now

syntax: (now [int-minutes-offset [int-index]])

Returns information about the current date and time as a list of integers. An optional time-zone offset can be specified in minutes in int-minutes-offset. This causes the time to be shifted forward or backward in time, before being split into separate date values.

An optional list-index in int-index makes now return a specific member in the result list.

The second example returns the Coordinated Universal Time (UTC) time value of seconds after January 1, 1970.

format	description
year	Gregorian calendar
month	(1–12)
day	(1–31)
hour	(0–23) UTC
minute	(0–59)
second	(0–59)
microsecond	(0–999999) OS-specific, millisecond resolution
day of current year	Jan 1st is 1
day of current week	(1–7) starting Monday
time zone offset in minutes	west of GMT
daylight savings time type	(0–6) on Linux/Unix or bias in minutes on MS Windows

Ranging from 0 to 23, hours are given in UTC and are not adjusted for the local time zone. The resolution of the microseconds field depends on the operating system and platform. On some platforms, the last three digits of the microseconds field are always 0 (zero).

The "day of the week" field starts with 1 on Monday conforming to the ISO 8601 international standard for date and time representation.

On some platforms, the daylight savings time flag is not active and returns 0 (zero) even during daylight savings time (dst).

Depending on the geographical area, the daylight savings time type (dst) has a different value from 1 to 6:

type	area
0	not on dst
1	USA style dst
2	Australian style dst
3	Western European dst
4	Middle European dst
5	Eastern European dst
6	Canada dst

nper

syntax: (nper num-interest num-pmt num-pv [num-fv [int-type]])

Calculates the number of payments required to pay a loan of num-pv with a constant interest rate of num-interest and payment num-pmt. If payment is at the end of the period, int-type is 0 (zero) or int-type is omitted; for payment at the beginning of each period, int-type is 1.

The example calculates the number of monthly payments required to pay a loan of $100,000 at a yearly interest rate of 7 percent with payments of $775.30.

npv

syntax: (npv num-interest list-values)

Calculates the net present value of an investment with a fixed interest rate num-interest and a series of future payments and income in list-values. Payments are represented by negative values in list-values, while income is represented by positive values in list-values.

In the example, an initial investment of $2,481.85 would allow for an income of $1,000 after the end of the first, second, and third years.

nth utf8

syntax: (nth int-index list)
syntax: (nth int-index array)
syntax: (nth int-index str)

syntax: (nth list-indices list)
syntax: (nth list-indices array)

In the first syntax group nth uses int-index an index into the list, array or str found and returning the element found at that index. See also Indexing elements of strings and lists.

Multiple indices may be specified to recursively access elements in nested lists or arrays. If there are more indices than nesting levels, the extra indices are ignored. When multiple indices are used, they must be put in a list as shown in the second syntax group.

The list L can be the context of the default functor L:L. This allows lists passed by reference:

Reference passing is faster and uses less memory in big lists and should be used on lists with more than a few hundred items.

Note that the implicit indexing version of nth is not breaking newLISP syntax rules but should be understood as a logical expansion of newLISP syntax rules to other data types than built-in functions or lambda expressions. A list in the functor position of an s-expression assumes self-indexing functionality using the index arguments following.

The implicit indexed syntax forms are faster but the other form with an explicit nth may be more readable in some situations.

In the String version, nth returns the character found at the position int-index in str and returns it as a string.

Note that nth works on character boundaries rather than byte boundaries when using the UTF-8–enabled version of newLISP. To access ASCII and binary string buffers on single byte boundaries use slice.

See also setf for modifying multidimensional lists and arrays and push and pop for modifying lists.

null?

syntax: (null? exp)

Checks if an expression evaluates to nil, the empty list (), the empty string "", NaN (not a number), or 0 (zero), in which case it returns true. In all other cases, null? returns nil. The predicate null? is useful in conjunction with the functions filter or clean to check the outcome of other newLISP operations.

number? bigint

syntax: (number? exp)

true is returned only if exp evaluates to a floating point number or an integer; otherwise, nil is returned.

odd? bigint

syntax: (odd? int-number)

Checks the parity of an integer number. If the number is not even divisible by 2, it has odd parity. When a floating point number is passed for int-number, it will be converted first to an integer by cutting off its fractional part.

open

syntax: (open str-path-file str-access-mode [str-option])

The str-path-file is a file name, and str-access-mode is a string specifying the file access mode. open returns an integer, which is a file handle to be used on subsequent read or write operations on the file. On failure, open returns nil. The access mode "write" creates the file if it doesn't exist, or it truncates an existing file to 0 (zero) bytes in length.

The first example uses open to set the device for print and writes the word "hello world" into the file newfile.data. The second example reads a byte value at offset 6 in the same file (the ASCII value of 'w' is 119). Note that using close on (device) automatically resets device to 0 (zero).

As an additional str-option, "non-block" or "n" can be specified after the "read" or "write" option. Only available on Unix systems, non-blocking mode can be useful when opening named pipes but is not required to perform I/O on named pipes.

syntax: (or exp-1 [exp-2 ... ])

Evaluates expressions exp-x from left to right until finding a result that does not evaluate to nil or the empty list (). The result is the return value of the or expression.

ostype

syntax: ostype

ostype is a built-in system constant containing the name of the operating system newLISP is running on.

One of the following strings is returned: "Linux", "BSD", "OSX", "Tru64Unix", "Solaris", "SunOS", "Windows", "Cygwin", or "OS/2".

For a table of other built-in system variables and symbols see the chapter System Symbols and Constants in the appendix.

pack

syntax: (pack str-format exp-1 [exp-2 ... ])
syntax: (pack str-format list)

syntax: (pack struct exp-1 [exp-2 ... ])
syntax: (pack struct list)

When the first parameter is a string, pack packs one or more expressions (exp-1 to exp-n) into a binary format specified in the format string str-format, and returning the binary structure in a string buffer. The symmetrical unpack function is used for unpacking. The expression arguments can also be given in a list. pack and unpack are useful when reading and writing binary files (see read and write) or when unpacking binary structures from return values of imported C functions using import.

When the first parameter is the symbol of a struct definition, pack uses the format as specified in struct. While pack with str-format literally packs as specified, pack with struct will insert structure aligning pad-bytes depending on data type, order of elements and CPU architecture. Refer to the description of the struct function for more detail.

format	description
`c`	a signed 8-bit number
`b`	an unsigned 8-bit number
`d`	a signed 16-bit short number
`u`	an unsigned 16-bit short number
`ld`	a signed 32-bit long number
`lu`	an unsigned 32-bit long number
`Ld`	a signed 64-bit long number
`Lu`	an unsigned 64-bit long number
`f`	a float in 32-bit representation
`lf`	a double float in 64-bit representation
`sn`	a string of n null padded ASCII characters
`nn`	n null characters
`>`	switch to big endian byte order
`<`	switch to little endian byte order

pack will convert all floats into integers when passed to b, c, d, ld, or lu formats. It will also convert integers into floats when passing them to f and lf formats.

The last two statements show how floating point numbers are converted into integers when required by the format specification.

Note that the list should be referenced directly in pack, so the pointers passed by adr are valid. adr would be written as char * adr[] in the C-programming language and represents a 32-bit pointer to an array of 32-bit string pointers.

The > and < specifiers can be used to switch between little endian and big endian byte order when packing or unpacking:

Switching the byte order will affect all number formats with 16-, 32-, or 64-bit sizes.

The examples show spaces between the format specifiers. These are not required but can be used to improve readability.

parse

syntax: (parse str-data [str-break [regex-option]])

Breaks the string that results from evaluating str-data into string tokens, which are then returned in a list. When no str-break is given, parse tokenizes according to newLISP's internal parsing rules. A string may be specified in str-break for tokenizing only at the occurrence of a string. If an regex-option number or string is specified, a regular expression pattern may be used in str-break.

When str-break is not specified, the maximum token size is 2048 for quoted strings and 256 for identifiers. In this case, newLISP uses the same faster tokenizer it uses for parsing newLISP source. If str-break is specified, there is no limitation on the length of tokens. A different algorithm is used that splits the source string str-data at the string in str-break.

The last two examples show a regular expression as the break string with the default option 0 (zero). Instead of { and } (left and right curly brackets), double quotes can be used to limit the pattern. In this case, double backslashes must be used inside the pattern. The last pattern could be used for parsing CSV (Comma Separated Values) files. For the regular expression option numbers, see regex.

peek

syntax: (peek int-handle)

Returns the number of bytes ready to be read on a file descriptor; otherwise, it returns nil if the file descriptor is invalid. peek can also be used to check stdin. This function is only available on Unix-like operating systems.

Use the net-peek function to check for network sockets, or for the number of available bytes on them. On Unix systems, net-peek can be used to check file descriptors. The difference is that net-peek also sets net-error.

pipe

syntax: (pipe)

Creates an inter-process communications pipe and returns the read and write handles to it within a list.

The pipe handles can be passed to a child process launched via process or to fork for inter-process communications.

Note that the pipe does not block when being written to, but it does block reading until bytes are available. A read-line blocks until a newline character is received. A read blocks when fewer characters than specified are available from a pipe that has not had the writing end closed by all processes.

newLISP can also use named pipes. See the open function for further information.

pmt

Calculates the payment for a loan based on a constant interest of num-interest and constant payments over num-periods of time. num-future-value is the value of the loan at the end (typically 0.0). If payment is at the end of the period, int-type is 0 (zero) or int-type is omitted; for payment at the beginning of each period, int-type is 1.

The above example calculates a payment of $775.30 for a loan of $100,000 at a yearly interest rate of 7 percent. It is calculated monthly and paid over 20 years (20 * 12 = 240 monthly periods). This illustrates the typical way payment is calculated for mortgages.

pop ! utf8

syntax: (pop list [int-index-1 [int-index-2 ... ]])
syntax: (pop list [list-indexes])

syntax: (pop str [int-index [int-length]])

In the first syntax, pop extracts an element from the list found by evaluating list. If a second parameter is present, the element at int-index is extracted and returned. See also Indexing elements of strings and lists.

In the second version, indices are specified in the list list-indexes. This way, pop works easily together with ref and ref-all, which return lists of indices.

pop-assoc !

syntax: (pop-assoc exp-key list-assoc)
syntax: (pop-assoc list-keys list-assoc)

Removes an association referred to by the key in exp-key from the association list in list-assoc and returns the popped expression.

See also assoc for retrieving associations and setf for modifying association lists.

post-url

syntax: (post-url str-url str-content [str-content-type [str-option] [int-timeout [ str-header]]])

Sends an HTTP POST request to the URL in str-url. POST requests are used to post information collected from web entry forms to a web site. Most of the time, the function post-url mimics what a web browser would do when sending information collected in an HTML form to a server, but it can also be used to upload files (see an HTTP reference). The function returns the page returned from the server in a string.

When post-url encounters an error, it returns a string description of the error beginning with ERR:.

The last parameter, int-timeout, is for an optional timeout value, which is specified in milliseconds. When no response from the host is received before the timeout has expired, the string ERR: timeout is returned.

The above example uploads a user name and city using a special format called application/x-www-form-urlencoded. post-url can be used to post other content types such as files or binary data. See an HTTP reference for other content-type specifications and data encoding formats. When the content-type parameter is omitted, post-url assumes application/x-www-form-urlencoded as the default content type.

Additional parameters

When str-content-type is specified, the optional str-option can take the same options as get-url for the returned content. If the int-timeout option is specified, the custom header option str-header can be specified, as well. See the function get-url for details on all options.

pow

syntax: (pow num-1 num-2 [num-3 ... ])
syntax: (pow num-1)

prefix

syntax: (prefix sym)

pretty-print

syntax: (pretty-print [int-length [str-tab [str-fp-format]])

Reformats expressions for print, save, or source and when printing in an interactive console. The first parameter, int-length, specifies the maximum line length, and str-tab specifies the string used to indent lines. The third parameter str-fp-format describes the default format for printing floating point numbers. All parameters are optional. pretty-print returns the current settings or the new settings when parameters are specified.

The first example reports the default settings of 80 for the maximum line length and a space character for indenting. The second example changes the line length to 90 and the indent to a TAB character. The third example changes the line length only. The last example changes the default format for floating point numbers. This is useful when printing unformatted floating point numbers without fractional parts, and these numbers should still be recognizable as floating point numbers. Without the custom format, x would be printed as 0 indistinguishable from floating point number. All situations where unformatted floating point numbers are printed, are affected.

Note that pretty-print cannot be used to prevent line breaks from being printed. To completely suppress pretty printing, use the function string to convert the expression to a raw unformatted string as follows:

primitive?

syntax: (primitive? exp)

Evaluates and tests if exp is a primitive symbol and returns true or nil depending on the result. All built-in functions and functions created using import are primitives.

syntax: (print exp-1 [exp-2 ... ])

Evaluates and prints exp-1— to the current I/O device, which defaults to the console window. See the built-in function device for details on how to specify a different I/O device.

List expressions are indented by the nesting levels of their opening parentheses.

Several special characters may be included in strings encoded with the escape character \:

character	description
`\n`	the line-feed character (ASCII 10)
`\r`	the carriage-return character (ASCII 13)
`\t`	the tab character (ASCII 9)
`\nnn`	where `nnn` is a decimal ASCII code between 000 and 255
`\xnn`	where `nn` is a hexadecimal ASCII code between 00 and FF

println

syntax: (println exp-1 [exp-2 ... ])

Evaluates and prints exp-1— to the current I/O device, which defaults to the console window. A line-feed is printed at the end. See the built-in function device for details on how to specify a different I/O device. println works exactly like print but emits a line-feed character at the end.

prob-chi2

syntax: (prob-chi2 num-chi2 int-df)

Returns the probability of an observed Chi² statistic in num-chi2 with num-df degrees of freedom to be equal or greater under the null hypothesis. prob-chi2 is derived from the incomplete Gamma function gammai.

prob-f

syntax: (prob-f num-f int-df1 int-df2)

Returns the probability of an observed F statistic in num-f with int-df1 and int-df2 degrees of freedom to be equal or greater under the null hypothesis.

prob-t

syntax: (prob-t num-t int-df1)

Returns the probability of an observed Student's t statistic in num-t with int-df degrees of freedom to be equal or greater under the null hypothesis.

prob-z

syntax: (prob-z num-z)

Returns the probability of num-z, not to exceed the observed value where num-z is a normal distributed value with a mean of 0.0 and a standard deviation of 1.0.

process

syntax: (process str-command)
syntax: (process str-command int-pipe-in int-pipe-out [int-win-option])
syntax: (process str-command int-pipe-in int-pipe-out [int-unix-pipe-error])

In the first syntax, process launches a process specified in str-command and immediately returns with a process ID or nil if a process could not be created. This process will execute the program specified or immediately die if str-command could not be executed.

On Mac OS X and other Unixes, the application or script must be specified with its full path-name. The new process inherits the OS environment from the parent process.

Command line arguments are parsed out at spaces. Arguments containing spaces must be delimited using single quotes on Mac OS X and other Unixes. On MS Windows, double quotes are used. The process id returned can be used to destroy the running process using destroy, if the process does not exit by itself.

If the path of the executable is unknown, exec together with the Unix which command can be used to start a program. The pid returned can be used to destroy the process.

In the second syntax, standard input and output of the created process can be redirected to pipe handles. When remapping standard I/O of the launched application to a pipe, it is possible to communicate with the other application via write-line and read-line or write and read statements:

On MS Windows versions of newLISP, a fourth optional parameter of int-win-option can be specified to control the display status of the application. This option defaults to 1 for showing the application's window, 0 for hiding it, and 2 for showing it minimized on the Windows launch bar.

On both MS Windows and Linux/Unix systems, standard error will be redirected to standard out by default. On Linux/Unix, an optional pipe handle for standard error output can be defined in int-unix-pipe-error.

Not all interactive console applications can have their standard I/O channels remapped. Sometimes only one channel, in or out, can be remapped. In this case, specify 0 (zero) for the unused channel. The following statement uses only the launched application's output:

Normally, two pipes are used: one for communications to the child process and the other one for communications from the child process.

See also the pipe and share functions for inter-process communications and the semaphore function for synchronization of several processes. See the fork and spawn functions for other ways of starting newLISP processes. Both are only available on Mac OS X, Linux and other Unix like operating systems.

prompt-event

syntax: (prompt-event sym-event-handler | func-event-handler)
syntax: (prompt-event nil)

Refines the prompt as shown in the interactive newLISP shell. The sym-event-handler or func-event-handler is either a symbol of a user-defined function or a lambda expression:

The current context before calling the prompt-event code is passed as a parameter to the function. Computer output is shown in bold.

The example redefines the > prompt to be the current context followed by a colon :, followed by the directory name, followed by the dollar symbol. Together with the command-event function this can be used to create fully customized shells or custom command interpreters.

The function in prompt-event must return a string of 63 characters maximum. Not returning a string will leave the prompt unchanged.

protected?

syntax: (protected? sym)

Checks if a symbol in sym is protected. Protected symbols are built-in functions, context symbols, and all symbols made constant using the constant function:

push ! utf8

syntax: (push exp list [int-index-1 [int-index-2 ... ]])
syntax: (push exp list [list-indexes])

syntax: (push str-1 str-2 [int-index])

Inserts the value of exp into the list list. If int-index is present, the element is inserted at that index. If the index is absent, the element is inserted at index 0 (zero), the first element. push is a destructive operation that changes the contents of the target list.

If more than one int-index is present, the indices are used to access a nested list structure. Improper indices (those not matching list elements) are discarded.

The second version takes a list of list-indexes but is otherwise identical to the first. In this way, push works easily together with ref and ref-all, which return lists of indices.

If list does not contain a list, list must contain a nil and will be initialized to the empty list.

Repeatedly using push to the end of a list using -1 as the int-index is optimized and as fast as pushing to the front of a list with no index at all. This can be used to efficiently grow a list.

Because push returns a reference to the modified list, pop can work on it directly.

In the third syntax push can be used to change strings. When int-index is used, it refers to character positions rather than byte positions. UTF-8 characters may be multi-byte characters.

put-url

syntax: (put-url str-url str-content [str-option] [int-timeout [str-header]])

The HTTP PUT protocol is used to transfer information in str-content to a file specified in str-url. The lesser-known HTTP PUT mode is frequently used for transferring web pages from HTML editors to Web servers. In order to use PUT mode, the web server's software must be configured correctly. On the Apache web server, use the 'Script PUT' directive in the section where directory access rights are configured.

If str-url starts with file:// then str-content is written to the local file system.

Optionally, an int-timeout value can be specified in milliseconds as the last parameter. put-url will return ERR: timeout when the host gives no response and the timeout expires. On other error conditions, put-url returns a string starting with ERR: and the description of the error.

The first example creates a file called myFile.txt on the target server and stores the text string 'Hi there' in it. In the second example, the local file webpage.html is transferred to asite.com.

The script put.cgi would contain code to receive content from the web server via STDIN. The following is a working put.cgi written in newLISP for the Apache web server:

Note that the script appends ".txt" to the path to avoid the CGI execution of uploaded malicious scripts. Note also that the two lines where the file path is composed may work differently in your web server environment. Check environment variables passed by your web server for composition of the right file path.

Additional parameters

In str-option can take the same options as get-url for the returned content. If the int-timeout option is specified, the custom header option str-header can be specified, as well. See the function get-url for details on all options.

See also the functions get-url and post-url, which can be used to upload files when formatting form data as multipart/form-data.

syntax: (pv num-int num-nper num-pmt [num-fv [int-type]])

Calculates the present value of a loan with the constant interest rate num-interest and the constant payment num-pmt after num-nper number of payments. The future value num-fv is assumed to be 0.0 if omitted. If payment is at the end of the period, int-type is 0 (zero) or int-type is omitted; for payment at the beginning of each period, int-type is 1.

In the example, a loan that would be paid off (future value = 0.0) in 240 payments of $775.30 at a constant interest rate of 7 percent per year would start out at $100,000.14.

quote

syntax: (quote exp)

Returns exp without evaluating it. The same effect can be obtained by prepending a ' (single quote) to exp. The function quote is resolved during runtime, the prepended ' quote is translated into a protective envelope (quote cell) during code translation.

quote?

syntax: (quote? exp)

Evaluates and tests whether exp is quoted. Returns true or nil depending on the result.

Note that in the set statement, ''x is quoted twice because the first quote is lost during the evaluation of the set assignment.

rand

syntax: (rand int-range [int-N])

Evaluates the expression in int-range and generates a random number in the range of 0 (zero) to (int-range - 1). When 0 (zero) is passed, the internal random generator is initialized using the current value returned by the C time() function. Optionally, a second parameter can be specified to return a list of length int-N of random numbers.

The first line in the example prints equally distributed 0's and 1's, while the second line produces a list of 100 integers with 0, 1, and 2 equally distributed. Use the random and normal functions to generate floating point random numbers, and use seed to vary the initial seed for random number generation.

random

syntax: (random float-offset float-scale int-n)
syntax: (random float-offset float-scale)

In the first form, random returns a list of int-n evenly distributed floating point numbers scaled (multiplied) by float-scale, with an added offset of float-offset. The starting point of the internal random generator can be seeded using seed.

When used in the second form, random returns a single evenly distributed number:

When no parameters are given, random assumes a mean of 0.0 and a standard deviation of 1.0.

randomize

syntax: (randomize list [bool])

randomize will always return a sequence different from the previous one without the optional bool flag. This may require the function to calculate several sets of reordered elements, which in turn may lead to different processing times with different invocations of the function on the same input list length. To allow for the output to be equal to the input, true or any expression evaluating to not nil must be specified in bool.

randomize uses an internal pseudo random sequence generator that returns the same series of results each time newLISP is started. Use the seed function to change this sequence.

read !

syntax: (read int-file sym-buffer int-size [str-wait])

Reads a maximum of int-size bytes from a file specified in int-file into a buffer in sym-buffer. Any data referenced by the symbol sym-buffer prior to the reading is deleted. The handle in int-file is obtained from a previous open statement. The symbol sym-buffer contains data of type string after the read operation. sym-buffer can also be a default functor specified by a context symbol for reference passing in and out of user-defined functions.

read is a shorter writing of read-buffer. The longer form still works but is deprecated and should be avoided in new code.

Optionally, a string to be waited for can be specified in str-wait. read will read a maximum amount of bytes specified in int-size or return earlier if str-wait was found in the data. The wait-string is part of the returned data and must not contain binary 0 (zero) characters.

Returns the number of bytes read or nil when the wait-string was not found. In any case, the bytes read are put into the buffer pointed to by sym-buffer, and the file pointer of the file read is moved forward. If no new bytes have been read, sym-buffer will contain nil.

Reads 1000 bytes or until the string password: is encountered. The string password: will be part of the data returned.

read-char

syntax: (read-char [int-file])

Reads a byte from a file specified by the file handle in int-file or from the current I/O device - e.g. stdin - when no file handle is specified. The file handle is obtained from a previous open operation. Each read-char advances the file pointer by one byte. Once the end of the file is reached, nil is returned.

Use read-line and device to read whole text lines at a time. Note that newLISP supplies a fast built-in function called copy-file for copying files.

read-expr

syntax: (read-expr str-source [sym-context [exp-error [int-offset]]])

read-expr parses the first expressions it finds in str-source and returns the translated expression without evaluating it. An optional context in sym-context specifies a namespace for the translated expression.

After a call to read-expr the system variable $count contains the number of characters scanned.

If an error occurs when translating str-source the expression in exp-error is evaluated and the result returned.

int-offset specifies an optional offset into str-source where processing should start. When calling read-expr repeatedly this number can be updated using $count, the number of characters processed.

Using read-expr a customized code reader can be programmed preprocessing expressions before evaluation.

read-file

syntax: (read-file str-file-name)

Reads a file in str-file-name in one swoop and returns a string buffer containing the data.

On failure the function returns nil. For error information, use sys-error when used on files. When used on URLs net-error gives more error information.

The file myfile is read, then encrypted using the password "secret" before being written back into a new file titled "myfile.enc" in the current directory.

read-file can take an http:// or file:// URL in str-file-name. When the prefix is http://, read-file works exactly like get-url and can take the same additional parameters.

The file somefile.tgz is retrieved from the remote location http://asite.com. The file transfer will time out after 10 seconds if it is not finished. In this mode, read-file can also be used to transfer files from remote newLISP server nodes.

read-key

syntax: (read-key)

Reads a key from the keyboard and returns an integer value. For navigation keys, more than one read-key call must be made. For keys representing ASCII characters, the return value is the same on all OSes, except for navigation keys and other control sequences like function keys, in which case the return values may vary on different OSes and configurations.

The last example can be used to check return sequences from navigation and function keys. To break out of the loop, press Ctrl-A.

Note that read-key will only work when newLISP is running in a Unix shell or Windows command shell. It will not work in the Java based newLISP-GS or Tcl/Tk based newLISP-Tk frontend. It will also not work when executed by newLISP Unix shared library or newLISP MS Windows DLL (Dynamic Link Library).

read-line

syntax: (read-line [int-file])

Reads from the current I/O device a string delimited by a line-feed character (ASCII 10). There is no limit to the length of the string that can be read. The line-feed character is not part of the returned string. The line always breaks on a line-feed, which is then swallowed. A line breaks on a carriage return (ASCII 13) only if followed by a line-feed, in which case both characters are discarded. A carriage return alone only breaks and is swallowed if it is the last character in the stream.

By default, the current device is the keyboard (device 0). Use the built-in function device to specify a different I/O device (e.g., a file). Optionally, a file handle can be specified in the int-file obtained from a previous open statement.

The last buffer contents from a read-line operation can be retrieved using current-line.

When read-line is reading from a file or from stdin in a CGI program or pipe, it will return nil when input is exhausted.

When using read-line on stdin, line length is limited to 2048 characters and performance is much faster.

The first example reads input from the keyboard and converts it to a number. In the second example, a file is read line-by-line and displayed on the screen. The write-line statement takes advantage of the fact that the result from the last read-line operation is stored in a system internal buffer. When write-line is used without argument, it writes the contents of the last read-line buffer to the screen.

read-utf8

syntax: (read-utf8 int-file)

Reads an UTF-8 character from a file specified by the file handle in int-file. The file handle is obtained from a previous open operation. Each read-utf8 advances the file pointer by the number of bytes contained in the UTF-8 character. Once the end of the file is reached, nil is returned.

The function returns an integer value which can be converted to a displayable UTF-8 character string using the char function.

The example reads a file containing UTF-8 encoded text and displays it to the terminal screen.

reader-event

syntax: (reader-event [sym-event-handler | func-event-handler])
syntax: (reader-event nil)

An event handler can be specified to hook between newLISP's reader, translation and evaluation process. The function specified in sym-event-handler or func-event-handler gets called after newLISP translates an expression and before evaluating it. The event handler can do transformation on the expression before it gets evaluated.

The following one-liner reader-event could be used to enhance the interactive shell with a tracer:

The reader event function will be called after each reading of an s-expression by the load or eval-string function.

In versions previous to 10.5.8 reader-event was used to define a macro expansion function in the module file macro.lsp. Starting version 10.5.8, newLISP has macro as a built-in function behaving the same, but much faster when loading files and reading source.

real-path

syntax: (real-path [str-path])
syntax: (real-path str-exec-name true)

In the first syntax real-path returns the full path from the relative file path given in str-path. If a path is not given, "." (the current directory) is assumed.

In the second syntax real-path returns the full path for an executable found given in str-exe-name. This syntax relies on an environment variable PATH defined on UNIX and Windows systems.

The output length is limited by the OS's maximum allowed path length. If real-path fails (e.g., because of a nonexistent path), nil is returned.

receive !

syntax: (receive int-pid sym-message)
syntax: (receive)

In the first syntax, the function is used for message exchange between child processes launched with spawn and their parent process. The message received replaces the contents in sym-message.

The function reads one message from the receiver queue of int-pid for each invocation. When the queue is empty, nil is returned.

To make receive blocking and wait for arriving messages, use the following form:

In the second syntax, the function returns a list of all child processes with pending messages for the parent process:

The list of child process IDs returned by (receive) only contains PIDs of processes which have unread messages in their send queues. The (receive pid msg) statement now can be issued non-blocking, because it always is guaranteed to find a pending message in a child's message queue.

For a more detailed discussion of this function and examples, see the send function.

ref

syntax: (ref exp-key list [func-compare [true]])

ref searches for the key expression exp-key in list and returns a list of integer indices or an empty list if exp-key cannot be found. ref can work together with push and pop, both of which can also take lists of indices.

By default, ref checks if expressions are equal. With func-compare, more complex comparison functions can be used. The comparison function can be a previously defined function. Note that this function always takes two arguments, even if only the second argument is used inside the function.

When the optional true parameter is present, the element found is returned instead of the index vector.

The following example shows the use of match and unify to formulate searches that are as powerful as regular expressions are for strings:

The '(X X) pattern with unify searches for a list pair where the two elements are equal. The unify pattern '(X g) searches for a list pair with the symbol g as the second member. The patterns are quoted to protect them from evaluation.

This is suitable when passing lists by reference using a context. See also the chapter Passing data by reference.

See also the ref-all function, which searches for all occurrences of a key expression in a nested list.

ref-all

syntax: (ref-all exp-key list [func-compare [true]])

Works similarly to ref, but returns a list of all index vectors found for exp-key in list.

When the optional true parameter is present, the elements found is returned of the index vectors.

By default, ref-all checks if expressions are equal. With func-compare, more complex comparison functions can be used.

The comparison function can be a previously defined function. Note that the comparison function always takes two arguments, even if only the second argument is used inside the function (as in the example using is-long?).

Using the match and unify functions, list searches can be formulated that are as powerful as regular expression searches are for strings.

regex

syntax: (regex str-pattern str-text [regex-option [int-offset]])

Performs a Perl Compatible Regular Expression (PCRE) search on str-text with the pattern specified in str-pattern. The same regular expression pattern matching is also supported in the functions directory, find, find-all, parse, replace, and search when using these functions on strings.

regex returns a list with the matched strings and substrings and the beginning and length of each string inside the text. If no match is found, it returns nil. The offset numbers can be used for subsequent processing.

Additionally a regex-option can be specified to control certain regular expression options explained later. Options can be given either by numbers or letters in a string.

The additional int-offset parameter tells regex to start searching for a match not at the beginning of the string but at an offset.

When no regex-option is present, the offset and length numbers in the regex results are given based bytes even when running the UTF-8 enabled version of newLISP. When specifying the PCRE_UTF8 option in regex-option only offset and length are reported in UTF8 characters.

regex also sets the variables $0, $1, and $2— to the expression and subexpressions found. Just like any other symbol in newLISP, these variables or their equivalent expressions ($ 0), ($ 1), and ($ 2)— can be used in other newLISP expressions for further processing.

Functions using regular expressions will not reset the $0, $1 ... $15 variables to nil when no match is found.

The second example shows the usage of extra options, while the third example demonstrates more complex parsing of two subexpressions that were marked by parentheses in the search pattern. In the last example, the expression and subexpressions are retrieved using the system variables $0 to $2 or their equivalent expression ($ 0) to ($ 2).

When "" (quotes) are used to delimit strings that include literal backslashes, the backslash must be doubled in the regular expression pattern. As an alternative, { } (curly brackets) or [text] and [/text] (text tags) can be used to delimit text strings. In these cases, no extra backslashes are required.

Characters escaped by a backslash in newLISP (e.g., the quote \" or \n) need not to be doubled in a regular expression pattern, which itself is delimited by quotes.

When curly brackets or text tags are used to delimit the pattern string instead of quotes, a simple backslash is sufficient. The pattern and string are then passed in raw form to the regular expression routines. When curly brackets are used inside a pattern itself delimited by curly brackets, the inner brackets must be balanced, as follows:

The following constants can be used for regex-option. Several options can be combined using a binary or | (pipe) operator. E.g. (| 1 4) would combine options 1 and 4 or "is" when using letters for the two options.

The last two options are specific for newLISP. The REPLACE_ONCE option is only to be used in replace; it can be combined with other PCRE options.

Multiple options can be combined using a + (plus) or | (or) operator, e.g.: (| PCRE_CASELESS PCRE_DOTALL) or "is" when using letters as options.

The settings of the PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, and PCRE_EXTENDED options can be changed from within the pattern by a sequence of option letters enclosed between "(?" and ")". The option letters are:

PCRE name	no	description
PCRE_CASELESS	1 or i	treat uppercase like lowercase
PCRE_MULTILINE	2 or m	limit search at a newline like Perl's /m
PCRE_DOTALL	4 or s	. (dot) also matches newline
PCRE_EXTENDED	8 or x	ignore whitespace except inside char class
PCRE_ANCHORED	16 or A	anchor at the start
PCRE_DOLLAR_ENDONLY	32 or D	$ matches at end of string, not before newline
PCRE_EXTRA	64	additional functionality currently not used
PCRE_NOTBOL	128	first ch, not start of line; ^ shouldn't match
PCRE_NOTEOL	256	last char, not end of line; $ shouldn't match
PCRE_UNGREEDY	512i or U	invert greediness of quantifiers
PCRE_NOTEMPTY	1024	empty string considered invalid
PCRE_UTF8	2048 or u	pattern and strings as UTF-8 characters
REPLACE_ONCE	0x8000	replace only one occurrence only for use in replace
PRECOMPILED	0x10000 or p	pattern is pre-compiled, can only be combined with RREPLACE_ONCE 0x8000

Note that regular expression syntax is very complex and feature-rich with many special characters and forms. Please consult a book or the PCRE manual pages for more detail. Most PERL books or introductions to Linux or Unix also contain chapters about regular expressions. See also http://www.pcre.org for further references and manual pages.

Regular expression patterns can be precompiled for higher speed when using changing repetitive patterns with regex-comp.

regex-comp

syntax: (regex-comp str-pattern [int-option])

newLISP automatically compiles regular expression patterns and caches the last compilation to speed up repetitive pattern searches. If patterns change from one to the next, but are repeated over and over again, then the caching of the last pattern is not sufficient. regex-comp can be used to pre-compile repetitive patterns to speed up regular expression searches:

When using pre-compiled patterns in any of the functions using regular expressions, the option number is set to 0x10000 to signal that pre-compiled patterns are used. Normal pattern options are specified during pre-compilation with regex-comp . The 0x10000 option can only be combined with 0x8000, the option used to specify that only one replacement should be made when using replace.

The function ends-with should not be used with compiled patterns, as it tries to append to an un-compiled pattern internally.

remove-dir

syntax: (remove-dir str-path)

Removes the directory whose path name is specified in str-path. The directory must be empty for remove-dir to succeed. Returns nil on failure.

rename-file

syntax: (rename-file str-path-old str-path-new)

Renames a file or directory entry given in the path name str-path-old to the name given in str-path-new. Returns nil or true depending on the operation's success.

replace !

syntax: (replace exp-key list exp-replacement [func-compare])
syntax: (replace exp-key list)

syntax: (replace str-key str-data exp-replacement)
syntax: (replace str-pattern str-data exp-replacement regex-option)

List replacement

If the second argument is a list, replace replaces all elements in the list list that are equal to the expression in exp-key. The element is replaced with exp-replacement. If exp-replacement is missing, all instances of exp-key will be deleted from list.

Note that replace is destructive. It changes the list passed to it and returns the changed list. The number of replacements made is contained in the system variable $count when the function returns. During executions of the replacement expression, the anaphoric system variable $it is set to the expression to be replaced.

Optionally, func-compare can specify a comparison operator or user-defined function. By default, func-compare is the = (equals sign).

Using the match and unify functions, list searches can be formulated that are as powerful as regular expression string searches:

List removal

The last form of replace has only two arguments: the expression exp and list. This form removes all exps found in list.

String replacement without regular expression

If all arguments are strings, replace replaces all occurrences of str-key in str-data with the evaluated exp-replacement, returning the changed string. The expression in exp-replacement is evaluated for every replacement. The number of replacements made is contained in the system variable $count. This form of replace can also process binary 0s (zeros).

Regular expression replacement

The presence of a fourth parameter indicates that a regular expression search should be performed with a regular expression pattern specified in str-pattern and an option number specified in regex-option (e.g., 1 (one) or "i" for case-insensitive searching or 0 (zero) for a standard Perl Compatible Regular Expression (PCRE) search without options). See regex above for details.

By default, replace replaces all occurrences of a search string even if a beginning-of-line specification is included in the search pattern. After each replace, a new search is started at a new position in str-data. Setting the option bit to 0x8000 in regex-option will force replace to replace only the first occurrence. The changed string is returned.

replace with regular expressions also sets the internal variables $0, $1, and $2— with the contents of the expressions and subexpressions found. The anaphoric system variable $it is set to the same value as $0. These can be used to perform replacements that depend on the content found during replacement. The symbols $it, $0, $1, and $2— can be used in expressions just like any other symbols. If the replacement expression evaluates to something other than a string, no replacement is made. As an alternative, the contents of these variables can also be accessed by using ($ 0), ($ 1), ($ 2), and so forth. This method allows indexed access (e.g., ($ i), where i is an integer).

After all replacements are made, the number of replacements is contained in the system variable $count.

The setf function together with nth, first or last can also be used to change elements in a list.

reset

syntax: (reset)
syntax: (reset true)
syntax: (reset int-max-cells)

In the first syntax, reset returns to the top level of evaluation, switches the trace mode off, and switches to the MAIN context/namespace. reset restores the top-level variable environment using the saved variable environments on the stack. It also throws an error "user reset - no error" which can be reported with user defined error handlers. Since version 10.5.5 reset also interrupts command line parameter processing.

reset walks through the entire cell space, which may take a few seconds in a heavily loaded system.

In the second syntax, reset will stop the current process and start a new clean newLISP process with the same command-line parameters. This mode will only work when newLISP was started using its full path-name, e.g. /usr/bin/newlisp instead of only newlisp. This mode is not available on MS Windows.

In the third syntax. reset will change the maximum cell count allowed in the system. This number is also reported as the second number in the list by sys-info. On 64-bit newLISP one lisp cell occupies 32 bytes, or 16 bytes on the 32-bit version. This does not include string memory, which may be pointed to by cells.

The minimum cell count is 4095, trying to specify less will set it to 4095. The program will exit when trying to allocate more.

Resetting the maximum cell count will not restart the system and can be done at any point in a program. Cell memory is allocated in blocks of 4095 cells, which is also initial minimum configuration.

rest utf8

syntax: (rest list)
syntax: (rest array)
syntax: (rest str)

Returns all of the items in a list or a string, except for the first. rest is equivalent to cdr or tail in other Lisp dialects.

In the second version, rest returns all but the first character of the string str in a string.

Note that an implicit rest is available for lists. See the chapter Implicit rest and slice.

Note that rest works on character boundaries rather than byte boundaries when the UTF-8–enabled version of newLISP is used.

reverse !

syntax: (reverse list)
syntax: (reverse array)
syntax: (reverse string)

In the first and second form, reverse reverses and returns the list or array. Note that reverse is destructive and changes the original list or array.

In the third form, reverse is used to reverse the order of characters in a string.

rotate !

syntax: (rotate list [int-count])
syntax: (rotate str [int-count])

Rotates and returns the list or string in str. A count can be optionally specified in int-count to rotate more than one position. If int-count is positive, the rotation is to the right; if int-count is negative, the rotation is to the left. If no int-count is specified, rotate rotates 1 to the right. rotate is a destructive function that changes the contents of the original list or string.

When working on a string, rotate works on byte boundaries rather than character boundaries.

round

syntax: (round number [int-digits])

Rounds the number in number to the number of digits given in int-digits. When decimals are being rounded, int-digits is negative. It is positive when the integer part of a number is being rounded.

save

syntax: (save str-file)
syntax: (save str-file sym-1 [sym-2 ... ])

In the first syntax, the save function writes the contents of the newLISP workspace (in textual form) to the file str-file. save is the inverse function of load. Using load on files created with save causes newLISP to return to the same state as when save was originally invoked. System symbols starting with the $ character (e.g., $0 from regular expressions or $main-args from the command-line), symbols of built-in functions and symbols containing nil are not saved.

In the second syntax, symbols can be supplied as arguments. If sym-n is supplied, only the definition of that symbol is saved. If sym-n evaluates to a context, all symbols in that context are saved. More than one symbol can be specified, and symbols and context symbols can be mixed. When contexts are saved, system variables and symbols starting with the $ character are not saved. Specifying system symbols explicitly causes them to be saved.

Each symbol is saved by means of a set statement or—if the symbol contains a lambda or lambda-macro function—by means of define or define-macro statements.

Because all context symbols are part of the context MAIN, saving MAIN saves all contexts.

Saving to a URL will cause an HTTP PUT request to be sent to the URL. In this mode, save can also be used to push program source to remote newLISP server nodes. Note that a double backslash is required when path names are specified relative to the root directory. save in HTTP mode will observe a 60-second timeout.

Symbols made using sym that are incompatible with the normal syntax rules for symbols are serialized using a sym statement instead of a set statement.

save serializes contexts and symbols as if the current context is MAIN. Regardless of the current context, save will always generate the same output.

See also the functions load (the inverse operation of save) and source, which saves symbols and contexts to a string instead of a file.

syntax: (search int-file str-search [bool-flag [regex-option]])

Searches a file specified by its handle in int-file for a string in str-search. int-file can be obtained from a previous open file. After the search, the file pointer is positioned at the beginning or the end of the searched string or at the end of the file if nothing is found.

By default, the file pointer is positioned at the beginning of the searched string. If bool-flag evaluates to true, then the file pointer is positioned at the end of the searched string.

In regex-option, the options flags can be specified to perform a PCRE regular expression search. See the function regex for details. If regex-option is not specified a faster, plain string search is performed. search returns the new file position or nil if nothing is found.

When using the regular expression options flag, patterns found are stored in the system variables $0 to $15.

The file init.lsp is opened and searched for the string define and the line in which the string occurs is printed.

The second example looks for all lines in the file program.c which start with the string #define and prints the rest of the line after the string "#define ".

seed

syntax: (seed int-seed)
syntax: (seed int-seed true [int-pre-N])
syntax: (seed)

Seeds the internal random generator that generates numbers for amb, normal, rand, and random with the number specified in int-seed. Note that the first syntax uses a random generator based on the C-library function rand(). All randomizing functions in newLISP are based on this function.

When using the second syntax, all randomizing functions are based on a random generator independent of platforms and compilers used to built newLISP. When seeding with the second syntax all random functions called subsequenly like amb, normal, rand, random and randomize are based on this platform independent random generator.

The optional int-pre-N specifies the number of random numbers to be pre- fetched as part of the seeding and initialization procedure. When this parameter is ommitted seed assumes 50.

Note that the maximum value for int-seed is limited to 16 or 32 bits, depending on the operating system used. Internally, only the 32 least significant bits are passed to the random seed function of the OS.

After using seed with the same number, the random generator starts the same sequence of numbers. This facilitates debugging when randomized data are involved. Using seed, the same random sequences can be generated over and over again.

The second example is useful for guaranteeing a different seed any time the program starts.

The following example shows usage of the internal seed state in the built-in random generator:

self

syntax: (self [int-index ... ])

The function self accesses the target object of a FOOP method. One or more int-index are used to access the object members. self is set by the : colon operator.

seek

syntax: (seek int-file [int-position])

Sets the file pointer to the new position int-position in the file specified by int-file.The new position is expressed as an offset from the beginning of the file, 0 (zero) meaning the beginning of the file. If no int-position is specified, seek returns the current position in the file. If int-file is 0 (zero), on BSD, seek will return the number of characters printed to STDOUT, and on Linux and MS Windows, it will return -1. On failure, seek returns nil. When int-position is set to -1, seek sets the file pointer to the end of the file.

seek can set the file position past the current end of the file. Subsequent writing to this position will extend the file and fill unused positions with zero's. The blocks of zeros are not actually allocated on disk, so the file takes up less space and is called a sparse file.

select utf8

syntax: (select list list-selection)
syntax: (select list [int-index_i ... ])

syntax: (select string list-selection)
syntax: (select string [int-index_i ... ])

In the first two forms, select picks one or more elements from list using one or more indices specified in list-selection or the int-index_i.

In the second two forms, select picks one or more characters from string using one or more indices specified in list-selection or the int-index_i.

Selected elements can be repeated and do not have to appear in order, although this speeds up processing. The order in list-selection or int-index_i can be changed to rearrange elements.

semaphore

syntax: (semaphore)
syntax: (semaphore int-id)
syntax: (semaphore int-id int-wait)
syntax: (semaphore int-id int-signal)
syntax: (semaphore int-id 0)

A semaphore is an interprocess synchronization object that maintains a count between 0 (zero) and some maximum value. Useful in controlling access to a shared resource, a semaphore is set to signaled when its count is greater than zero and to non-signaled when its count is zero.

A semaphore is created using the first syntax. This returns the semaphore ID, an integer used subsequently as int-id when the semaphore function is called. Initially, the semaphore has a value of zero, which represents the non-signaled state.

If calling semaphore with a negative value in int-wait causes it to be decremented below zero, the function call will block until another process signals the semaphore with a positive value in int-signal. Calls to the semaphore with int-wait or int-signal effectively try to increment or decrement the semaphore value by a positive or negative value specified in int-signal or int-wait. Because the value of a semaphore must never fall below zero, the function call will block when this is attempted (i.e., a semaphore with a value of zero will block until another process increases the value with a positive int-signal).

The second syntax is used to inquire about the value of a semaphore by calling semaphore with the int-id only. This form is not available on MS Windows.

Supplying 0 (zero) as the last argument will release system resources for the semaphore, which then becomes unavailable. Any pending waits on this semaphore in other child processes will be released.

On MS Windows, only parent and child processes can share a semaphore. On Linux/Unix, independent processes can share a semaphore.

On failure the semaphore function returns nil. sys-error can be used to retrieve the error number and text from the underlying operating system.

After the semaphore is acquired in sid, it has a value of 0 (the non-signaled state). When starting the process counter, the semaphore will block after the initial start message and will wait in the semaphore call. The -1 is trying to decrement the semaphore, which is not possible because its value is already zero. In the interactive, main parent process, the semaphore is signaled by raising its value by 1. This unblocks the semaphore call in the counter process, which can now decrement the semaphore from 1 to 0 and execute the print statement. When the semaphore call is reached again, it will block because the semaphore is already in the wait (0) state.

Subsequent calls to semaphore with numbers greater than 1 give the counter process an opportunity to decrement the semaphore several times before blocking.

More than one process can participate in controlling the semaphore, just as more than one semaphore can be created. The maximum number of semaphores is controlled by a system-wide kernel setting on Unix-like operating systems.

Use the fork function to start a new process and the share function to share information between processes. For a more comprehensive example of using semaphore to synchronize processes, see the file prodcons.lsp example in the examples directory in the source distribution, as well as the examples and modules distributed with newLISP.

send

syntax: (send int-pid exp)
syntax: (send)

The send function enables communication between parent and child processes started with spawn. Parent processes can send and receive messages to and from their child processes and child processes can send and receive messages to and from their parent process. A proxy technique – shown further down – is employed to communicate between child process peers. send and receive do not require locks or semaphores. They work on dual send and receive message queues.

Processes started using fork or process can not use send and receive message functions. Instead they should use either share with semaphore or pipe to communicate.

In the first syntax send is used to send a message from a parent to a child process or a child to a parent process.

The second syntax is only used by parent processes to get a list of all child processes ready to accept message from the parent in their receive queues. If a child's receive queue is full, it will not be part of the list returned by the (send) statement.

The content of a message may be any newLISP expression either atomic or list expressions: boolean constants nil and true, integers, floating point numbers or strings, or any list expression in valid newLISP syntax. The size of a message is unlimited.

The exp parameter specifies the data to be sent to the recipient in int-pid. The recipient can be either a spawned child process of the current process or the parent process. If a message queue is full, it can be read from the receiving end, but a send issued on the other side of the queue will fail and return nil.

When the send queue is full, send will return nil until enough message content is read on the receiving side of the queue and the queue is ready to accept new messages from send statements.

Using the until looping function, the message statements can be repeated until they return a value not nil. This way, non-blocking send and receive can be made blocking until they succeed:

The sender statement blocks until the message could be deposited in the recipients queue.

The receive statement blocks until a new message can be fetched from the queue.

As the until statements in this example lack body expressions, the last value of the evaluated conditional expression is the return value of the until loop.

Blocking message exchange

The following code shows how a recipient can listen for incoming messages, and in turn how a sender can retry to deposit a message into a queue. The example shows 5 child processes constantly delivering status data to a parent process which will display the data. After three data sets have been read, the parent will abort all child processes and exit:

The (sync) expression returns a list of all child PIDs, and (until (receive cpid msg)) is used to force a wait until status messages are received for each of the child processes.

A timeout mechanism could be part of an until or while loop to stop waiting after certain time has expired.

The examples show messages flowing from a child processes to a parent process, in the same fashion messages could flow into the other direction from parent to child processes. In that case the parent process would use (send) to obtain a list of child processes with place in their message queues.

Messages containing code for evaluation

The most powerful feature of the message functions is the ability to send any newLISP expression, which then can be evaluated by the recipient. The recipient uses eval to evaluate the received expression. Symbols contained in the expression are evaluated in the receivers environment.

The following example shows how a parent process acts like a message proxy. The parent receives messages from a child process A and routes them to a second child process with ID B. In effect this implements messages between child process peers. The implementation relies on the fact that the recipient can evaluate expressions contained in messages received. These expressions can be any valid newLISP statements:

Child process A sends three messages to B. As this cannot be done directly A sends send statements to the parent for evaluation. The statement:

will be evaluated in the environment of the parent process. Even so the variables A and B are bound to nil in the sender process A, in the parent process they will be bound to the correct process ID numbers.

is sent to the parent process. Once evaluated, it will cause the until loop to finish.

For more details on send and receive and more examples see the Code Patterns document.

sequence

syntax: (sequence num-start num-end [num-step])

Generates a sequence of numbers from num-start to num-end with an optional step size of num-step. When num-step is omitted, the value 1 (one) is assumed. The generated numbers are of type integer (when no optional step size is specified) or floating point (when the optional step size is present).

Note that the step size must be a positive number, even if sequencing from a higher to a lower number.

series

syntax: (series num-start num-factor num-count)
syntax: (series exp-start func num-count)

In the first syntax, series creates a geometric sequence with num-count elements starting with the element in num-start. Each subsequent element is multiplied by num-factor. The generated numbers are always floating point numbers.

In the second syntax, series uses a function specified in func to transform the previous expression in to the next expression:

The first example shows a series converging to the golden ratio, φ (for any starting value). The second example shows how func can be defined previously for better readability of the series statement.

The series function also updates the internal list $idx index value, which can be used inside func.

set !

syntax: (set sym-1 exp-1 [sym-2 exp-2 ... ])

Evaluates both arguments and then assigns the result of exp to the symbol found in sym. The set expression returns the result of the assignment. The assignment is performed by copying the contents of the right side into the symbol. The old contents of the symbol are deleted. An error message results when trying to change the contents of the symbols nil, true, or a context symbol. set can take multiple argument pairs.

The symbol for assignment could be the result from another newLISP expression. Expressions can refer to variables in the set expression.

Symbols can be set to lambda or lambda-macro expressions. This operation is equivalent to using define or define-macro.

Use the constant function (which works like set) to protect the symbol from subsequent alteration. Using the setq or setf function eliminates the need to quote the variable symbol.

set-locale

syntax: (set-locale [str-locale [int-category]])

Reports or switches to a different locale on your operating system or platform. When used without arguments, set-locale reports the current locale being used. When str-locale is specified, set-locale switches to the locale with all category options turned on (LC_ALL). Placing an empty string in str-locale switches to the default locale used on the current platform.

set-locale returns either the current locale string and decimal point string in a list or nil if the requested change could not be performed.

By default, newLISP – if not enabled for UTF-8 – starts up with the POSIX C default locale. This guarantees that newLISP's behavior will be identical on any platform locale. On UTF-8 enabled versions of newLISP the locale of the current platform is chosen.

In int-category integer numbers may be specified as category options for fine-tuning certain aspects of the locale, such as number display, date display, and so forth. The options valid on your platform can be found in the C include file locale.h and may be different on each platform. When no int-category is specified, LC_ALL is used to turn on all options for that locale.

Category	Mac OS X, BSDs & MS Windows
LC_ALL	0
LC_COLLATE	1
LC_CTYPE	2
LC_MONETARY	3
LC_NUMERIC	4
LC_TIME	5

Note that using set-locale does not change the behavior of regular expressions in newLISP. To localize the behavior of PCRE (Perl Compatible Regular Expressions), newLISP must be compiled with different character tables. See the file, LOCALIZATION, in the newLISP source distribution for details.

set-ref !

syntax: (set-ref exp-key list exp-replacement [func-compare])

Searches for exp-key in list and replaces the found element with exp-replacement. The list can be nested. The system variables $it contains the expression found and can be used in exp-replacement. The function returns the new modified list.

data could be the context identifier of a default function for passing lists by reference:

set-ref-all !

syntax: (set-ref-all exp-key list exp-replacement [func-compare])

Searches for exp-key in list and replaces each instance of the found element with exp-replacement. The list can be nested. The system variable $it contains the expression found and can be used in exp-replacement. The system variable $count contains the number of replacements made. The function returns the new modified list.

Using the default functor in the (list key) pattern allows the list to be passed by reference to a user-defined function containing a set-ref-all statement. This would result in less memory usage and higher speeds in when doing replacements in large lists:

When evaluating (foo db), the list in db:db will be passed by reference and set-ref-all will make the changes on the original, not on a copy of db:db.

The example sums all numbers found in records starting with the symbol oranges. The found items appear in $it

setq setf !

syntax: (setq place-1 exp-1 [place-2 exp-2 ... ])

setq and setf work alike in newLISP and set the contents of a symbol, list, array or string or of a list, array or string place reference. Like set, setq and setf can take multiple argument pairs. Although both setq and setf point to the same built-in function internally, throughout this manual setq is used when setting a symbol reference and setf is used when setting list or array references.

Often the new value set is dependent on the old value. setf can use the anaphoric system variable $it to refer to the old value inside the setf expression:

sgn

syntax: (sgn num)
syntax: (sgn num exp-1 [exp-2 [exp-3]])

In the first syntax, the sgn function is a logical function that extracts the sign of a real number according to the following rules:

In the second syntax, the result of evaluating one of the optional expressions exp-1, exp-2, or exp-3 is returned, instead of -1, 0, or 1. If exp-n is missing for the case triggered, then nil is returned.

syntax: (share)
syntax: (share int-address-or-handle)
syntax: (share int-address-or-handle exp-value)

syntax: (share nil int-address)

Accesses shared memory for communicating between several newLISP processes. When called without arguments, share requests a page of shared memory from the operating system. This returns a memory address on Linux/Unix and a handle on MS Windows, which can then be assigned to a variable for later reference. This function is not available on OS/2.

To set the contents of shared memory, use the third syntax of share. Supply a shared memory address on Linux/Unix or a handle on MS Windows in int-address-or-handle, along with an integer, float, string expression or any other expression (since v.10.1.0) supplied in exp-value. Using this syntax, the value supplied in exp-value is also the return value.

To access the contents of shared memory, use the second syntax of share, supplying only the shared memory address or handle. The return value will be any constant or expression (since v.10.1.0) written previously into the memory. If the memory has not been previously set to a value, nil will be returned.

Only available on Unix-like operating systems, the last syntax unmaps a shared memory address. Note that using a shared address after unmapping it will crash the system.

Memory can be shared between parent and child processes, but not between independent processes.

Since 10.1.0 size of share objects can exceed the shared memory pagesize of the operating system. For objects bigger than the pagesize, newLISP internally uses files for sharing. This requires a /tmp directory on Unix-like operating system. On MS Windows systems the environment variable TEMP must be set.

Expression read from shared memory and evaluated, will be evaluated in the recipient's process environment.

Note that shared memory access between different processes should be synchronized using a semaphore. Simultaneous access to shared memory can crash the running process.

For a more comprehensive example of using shared memory in a multi process Linux/Unix application, see the file example/prodcons.lsp in the newLISP source distribution.

signal

syntax: (signal int-signal sym-event-handler | func-event-handler)
syntax: (signal int-signal "ignore" | "default" | "reset")
syntax: (signal int-signal)

Sets a user-defined handler in sym-event-handler for a signal specified in int-signal or sets to a function expression in func-event-handler.

If no signal handler is specified any of the string constants "ignore", "default" or "reset" can be specified in either lower or upper case or simply using the first letter of the option string. When signal setup with any of these three options has been successful, true is returned.

Using "ignore" will make newLISP ignore the signal. Using "default" will set the handler to the default handler of the underlying platform OS. The "reset" option will restore the handler to newLISP startup state.

On startup, newLISP either specifies an empty newLISP handler or a Ctrl-C handler for SIGINT and a waitpipd(-1, 0, WNOHANG) C-call for SIGCHLD.

Different signals are available on different OS platforms and Linux/Unix flavors. The numbers to specify in int-signal also differ from platform-to-platform. Valid values can normally be extracted from a file found in /usr/include/sys/signal.h or /usr/include/signal.h.

Some signals make newLISP exit even after a user-defined handler has been specified and executed (e.g., signal SIGKILL). This behavior may also be different on different platforms.

On MS Windows, the above example would execute the handler before exiting newLISP. On most Linux/Unix systems, newLISP would stay loaded and the prompt would appear after hitting the [enter] key.

Instead of specifying a symbol containing the signal handler, a function can be specified directly. The signal number is passed as a parameter:

Note that the signal SIGKILL (9 on most platforms) will always terminate the application regardless of an existing signal handler.

The signal could also have been sent from another newLISP application using the function destroy:

If newLISP receives a signal while evaluating another function, it will still accept the signal and the handler function will be executed:

Specifying only a signal number will return either the name of the currently defined handler function or nil.

silent

syntax: (silent [exp-1 [exp-2 ... ]])

Evaluates one or more expressions in exp-1—. silent is similar to begin, but it suppresses console output of the return value and the following prompt. It is often used when communicating from a remote application with newLISP (e.g., GUI front-ends or other applications controlling newLISP), and the return value is of no interest.

Silent mode is reset when returning to a prompt. This way, it can also be used without arguments in a batch of expressions. When in interactive mode, hit [enter] twice after a statement using silent to get the prompt back.

sin

syntax: (sin num-radians)

sinh

syntax: (sinh num-radians)

Calculates the hyperbolic sine of num-radians. The hyperbolic sine is defined mathematically as: (exp (x) - exp (-x)) / 2. An overflow to inf may occur if num-radians is too large.

sleep

syntax: (sleep num-milliseconds)

Gives up CPU time to other processes for the amount of milliseconds specified in num-milli-seconds.

On some platforms, sleep is only available with a resolution of one second. In this case, the parameter int-milli-seconds will be rounded to the nearest full second.

A sleep may be cut short by a finishing child process started with fork or spawn.

slice

syntax: (slice list int-index [int-length])
syntax: (slice array int-index [int-length])
syntax: (slice str int-index [int-length])

In the first form, slice copies a sublist from a list. The original list is left unchanged. The sublist extracted starts at index int-index and has a length of int-length. If int-length is negative, slice will take the parameter as offset counting from the end and copy up to that offset. If the parameter is omitted, slice copies all of the elements to the end of the list.

In the second form, a part of the string in str is extracted. int-index contains the start index and int-length contains the length of the substring. If int-length is not specified, everything to the end of the string is extracted. slice also works on string buffers containing binary data like 0's (zeroes). It operates on byte boundaries rather than character boundaries. See also Indexing elements of strings and lists.

Note that slice always works on single 8-bit byte boundaries for offset and length numbers, even when running the UTF-8 enabled version of newLISP.

Note that an implicit slice is available for lists. See the chapter Implicit rest and slice.

Be aware that slice always works on byte boundaries rather than character boundaries in the UTF-8–enabled version of newLISP. As a result, slice can be used to manipulate binary content.

sort !

syntax: (sort list [func-compare])
syntax: (sort array [func-compare])

All members in list or array are sorted in ascending order. Anything may be sorted, regardless of the types. When members are themselves lists or arrays, each element is recursively compared. If two expressions of different types are compared, the lower type is sorted before the higher type in the following order:

The sort is destructive, changing the order of the elements in the original list or array and returning the sorted list or array. It is a stable binary merge-sort with approximately O(n log2 n) performance preserving the order of adjacent elements which are equal. When func-compare is used it must work with either <= or >= operators to be stable.

An optional comparison operator, user-defined function, or anonymous function can be supplied. The functor or operator can be given with or without a preceding quote.

source

syntax: (source)
syntax: (source sym-1 [sym-2 ... ])

Works almost identically to save, except symbols and contexts get serialized to a string instead of being written to a file. Multiple variable symbols, definitions, and contexts can be specified. If no argument is given, source serializes the entire newLISP workspace. When context symbols are serialized, any symbols contained within that context will be serialized, as well. Symbols containing nil are not serialized. System symbols beginning with the $ (dollar sign) character are only serialized when mentioned explicitly.

Symbols not belonging to the current context are written out with their context prefix.

As with save, the formatting of line breaks and leading spaces or tabs can be controlled using the pretty-print function.

spawn

syntax: (spawn sym exp [true])

Launches the evaluation of exp as a child process and immediately returns. The symbol in sym is quoted and receives the result of the evaluation when the function sync is executed. spawn is used to start parallel evaluation of expressions in concurrent processes. If newLISP is running on a multi-core CPU, the underlying operating system will distribute spawned processes onto different cores, thereby evaluating expressions in parallel and speeding up overall processing.

The optional true parameter must be set if send or receive is used to communicated with the child process spawned.

After successfully starting a child process, the spawn expression returns the process id of the forked process. The following examples shows how the calculation of a range of prime numbers can be split up in four sub ranges to speed up the calculation of the whole range:

On a 1.83 Intel Core 2 Duo processor, the above example will finish after about 13 seconds. Calculating all primes using (primes 1 4000000) would take about 20 seconds.

The sync function will wait for all child processes to finish and receive the evaluation results in the symbols p1 to p4. When all results are collected, sync will stop waiting and return true. When the time specified was insufficient , sync will return nil and another sync statement could be given to further wait and collect results. A short timeout time can be used to do other processing during waiting:

sync when used without any parameters, will not wait but immediately return a list of pending child processes. For the primes example, the following sync expression could be used to watch the progress:

A parameter of -1 tells sync to wait for a very long time (~ 1193 hours). A better solution would be to wait for a maximum time, then abort all pending child processes:

The three functions spawn, sync and abort are part of the Cilk API. The original implementation also does sophisticated scheduling and allocation of threaded tasks to multiple CPU cores. The newLISP implementation of the Cilk API lets the operating system of the underlying platform handle process management. Internally, the API is implemented using the Unix libc functions fork(), waitpid() and kill(). Intercommunications between processes and child processes is done using the send and receive functions.

With (fibo 7) 41 processes will be generated. Although the above code shows the working of the Cilk API in a recursive application, it would not be practical, as the overhead required to spawn subtasks is much higher than the time saved through parallelization.

Since version 10.1 a send and receive message functions are available for communications between parent and child processes. Using these functions any data or expression of any size can be transferred. Additionally messaged expressions can be evaluated in the recipient's environment.

sqrt

syntax: (sqrt num)

ssq

syntax: (ssq list-vector | array-vector)

Calculates the sum of squares of numbers in a vector in list-vector or array-vector.

starts-with

syntax: (starts-with str str-key [num-option])
syntax: (starts-with list [exp])

In the first version, starts-with checks if the string str starts with a key string in str-key and returns true or nil depending on the outcome.

If a regular expression number is specified in num-option, str-key contains a regular expression pattern. See regex for valid option numbers.

In the second version, starts-with checks to see if a list starts with the list element in exp. true or nil is returned depending on outcome.

stats

syntax: (stats list-vector)

The functions calculates statistical values of central tendency and distribution moments of values in list-vector. The following values are returned by stats in a list:

name	description
N	Number of values
mean	Mean of values
avdev	Average deviation from mean value
sdev	Standard deviation (population estimate)
var	Variance (population estimate)
skew	Skew of distribution
kurt	Kurtosis of distribution

The following example uses the list output from the stats expression as an argument for the format statement:

string

syntax: (string exp-1 [exp-2 ... ])

Translates into a string anything that results from evaluating exp-1—. If more than one expression is specified, the resulting strings are concatenated.

If a buffer passed to string contains \000, only the string up to the first terminating zero will be copied:

Use the append and join (allows the joining string to be specified) functions to concatenate strings containing zero bytes. Use the source function to convert a lambda expression into its newLISP source string representation.

string?

syntax: (string? exp)

Evaluates exp and tests to see if it is a string. Returns true or nil depending on the result.

struct

syntax: (struct symbol [str-data-type ... ])

The struct function can be used to define aggregate data types for usage with the extended syntax of import, pack and unpack, available on all versions of newLISP compiled with libffi. This allows importing functions which take C-language struct data types or pointers to these aggregate data types.

The following example illustrates the usage of struct together with the C data functions localtime and asctime. The localtime functions works similar to the built-in now function. The asctime function takes the numerical data output by localtime and formats these to readable text.

Care must be taken to pass valid addresses to pointer parameters in imported functions or when passing address pointers to unpack. Invalid address pointers can crash newLISP or make it unstable.

sub

syntax: (sub num-1 [num-2 ... ])

Successively subtracts the expressions in num-1, num-2—. sub performs mixed-type arithmetic and handles integers or floating points, but it will always return a floating point number. If only one argument is supplied, its sign is reversed. Any floating point calculation with NaN also returns NaN.

swap !

syntax: (swap place-1 place-2)

The contents of the two places place-1 and place-2 are swapped. A place can be the contents of an unquoted symbol or any list or array references expressed with nth, first, last or implicit indexing or places referenced by assoc or lookup.

swap is a destructive operation that changes the contents of the lists, arrays, or symbols involved.

sym

syntax: (sym string [sym-context [nil-flag]])
syntax: (sym number [sym-context [nil-flag]])
syntax: (sym symbol [sym-context [nil-flag]])

Translates the first argument in string, number, or symbol into a symbol and returns it. If the optional context is not specified in sym-context, the current context is used when doing symbol lookup or creation. Symbols will be created if they do not already exist. When the context does not exist and the context is specified by a quoted symbol, the symbol also gets created. If the context specification is unquoted, the context is the specified name or the context specification is a variable containing the context.

sym can create symbols within the symbol table that are not legal symbols in newLISP source code (e.g., numbers or names containing special characters such as parentheses, colons, etc.). This makes sym usable as a function for associative memory access, much like hash table access in other scripting languages.

As a third optional argument, nil can be specified to suppress symbol creation if the symbol is not found. In this case, sym returns nil if the symbol looked up does not exist. Using this last form, sym can be used to check for the existence of a symbol.

Because the function sym returns the symbol looked up or created, expressions with sym can be embedded directly in other expressions that use symbols as arguments. The following example shows the use of sym as a hash-like function for associative memory access, as well as symbol configurations that are not legal newLISP symbols:

The third syntax allows symbols to be used instead of strings for the symbol name in the target context. In this case, sym will extract the name from the symbol and use it as the name string for the symbol in the target context:

The def-context macro shows how this could be used to create a macro that creates contexts and their variables in a dynamic fashion.

A syntax of the context function can also be used to create, set and evaluate symbols.

symbol?

syntax: (symbol? exp)

Evaluates the exp expression and returns true if the value is a symbol; otherwise, it returns nil.

The first statement sets the contents of x to the symbol y. The second statement then checks the contents of x. The last example checks the first element of a list.

symbols

syntax: (symbols [context])

Returns a sorted list of all symbols in the current context when called without an argument. If a context symbol is specified, symbols defined in that context are returned.

sync

syntax: (sync int-timeout [func-inlet])
syntax: (sync)

When int-timeout in milliseconds is specified, sync waits for child processes launched with spawn to finish. Whenever a child process finishes, sync assigns the evaluation result of the spawned subtask to the symbol specified in the spawn statement. The sync returns true if all child processes have been processed or nil if the timeout value has been reached and more child processes are pending.

If sync additionally is given with an optional user-defined inlet function in func-inlet, this function will be called with the child process-id as argument whenever a spawned child process returns. func-inlet can contain either a lambda expression or a symbol which defines a function.

Without any parameter, sync returns a list of pending child process PIDs (process identifiers), for which results have not been processed yet.

When sync is given with a timeout parameter, it will block until timeout or until all child processes have returned, whichever comes earlier. When no parameter is specified or a function is specified, sync returns immediately.

The function sync is part of the Cilk API for synchronizing child processes and process parallelization. See the reference for the function spawn for a full discussion of the Cilk API.

sys-error

syntax: (sys-error)
syntax: (sys-error int-error)
syntax: (sys-error 0)

Reports the last error generated by the underlying OS which newLISP is running on. The error reported may differ on the platforms newLISP has been compiled for. Consult the platform's C library information. The error is reported as a list of error number and error text.

If no error has occurred or the system error number has been reset, nil is returned.

When int-error is greater 0 (zero) a list of the number and the error text is returned.

Whenever a function in newLISP within the system resources area returns nil, sys-error can be checked for the underlying reason. For file operations, sys-error may be set for nonexistent files or wrong permissions when accessing the resource. Another cause of error could be the exhaustion of certain system resources like file handles or semaphores.

sys-info

syntax: (sys-info [int-idx])

Calling sys-info without int-idx returns a list of internal resource statistics. Ten integers report the following status:

It is recommended to use offsets 0 to 5 to address up and including "Maximum call stack constant" and to use negative offsets -1 to -4 to access the last four entries in the system info list. Future new entries will be inserted after offset 5. This way older source code does not need to change.

offset	description
0	Number of Lisp cells
1	Maximum number of Lisp cells constant
2	Number of symbols
3	Evaluation/recursion level
4	Environment stack level
5	Maximum call stack constant
6	Pid of the parent process or 0
7	Pid of running newLISP process
8	Version number as an integer constant
9	Operating system constant: linux=1, bsd=2, osx=3, solaris=4, windows=6, os/2=7, cygwin=8, tru64 unix=9, aix=10, android=11 bit 11 will be set for ffilib (extended import/callback API) versions (add 1024) bit 10 will be set for IPv6 versions (add 512) bit 9 will be set for 64-bit (changeable at runtime) versions (add 256) bit 8 will be set for UTF-8 versions (add 128) bit 7 will be added for library versions (add 64)

The number for the maximum of Lisp cells can be changed via the -m command-line switch. For each megabyte of Lisp cell memory, 64k memory cells can be allocated. The maximum call stack depth can be changed using the -s command-line switch.

t-test

syntax: (t-test list-vector number-value)
syntax: (t-test list-vector-A list-vector-B [true])
syntax: (t-test list-vector-A list-vector-B float-probability)

In the first syntax the function uses a one sample Student's t test to compare the mean value of list-vector to the value in number-value:

In above example the difference of the mean value 4.125 from 2.5 is moderately significant. With a probability p = 0.021 (2.1%) the null hypothesis that the mean is not significantly different, can be rejected.

In the second syntax, the function performs a t-test using the Student's t statistic for comparing the means values in list-vector-A and list-vector-B. If the true flag is not used, both vectors in A and B can be of different length and groups represented by A and B are not related.

When the optional flag is set to true, measurements were taken from the same group twice, e.g. before and after a procedure.

The first example studies the effect of different sleep length before a test on the SCAT (Sam's Cognitive Ability Test):

The duration of sleeps before the SCAT does not have a significant effect with a probability value of 0.411.

In the second example, the same group of people get tested twice, before and after a treatment with Prozac depression medication:

The effect of the antidepressant treatment is moderately significant with a p of 0.0137.

In the third syntax, a form of the Student's t called Welch's t-test is performed. This method is used when the variances observed in both samples are significantly different. The threshold can be set using the float-probability parameter. When this parameter is used the t-test function will perform a F-test to compare the variances in the two data samples. If the probability of the found F-ratio is below the float-probability parameter, the Welch's t-test method will be used. Specifying this value as 1.0 effectively forces a Welch's t-test:

There is no significant difference between the means of the two samples. The Welch method of the t-test is slightly more sensitive in this case than using the normal t-test method.

Smaller values than 1.0 would trigger the Welch's t-test method only when the significance of variance difference in the samples reaches certain value.

tan

syntax: (tan num-radians)

tanh

syntax: (tanh num-radians)

Calculates the hyperbolic tangent of num-radians. The hyperbolic tangent is defined mathematically as: sinh (x) / cosh (x).

term

syntax: (term symbol)

throw

syntax: (throw exp)

Works together with the catch function. throw forces the return of a previous catch statement and puts the exp into the result symbol of catch.

The last example shows a shorter form of catch, which returns the throw result directly.

throw is useful for breaking out of a loop or for early return from user-defined functions or expression blocks. In the following example, the begin block will return X if (foo X) is true; else Y will be returned:

throw will not cause an error exception. Use throw-error to throw user error exceptions.

throw-error

syntax: (throw-error exp)

The user error can be handled like any other error exception using user-defined error handlers and the error-event function, or the form of catch that can capture error exceptions.

time

syntax: (time exp [int-count)

Evaluates the expression in exp and returns the time spent on evaluation in floating point milliseconds. Depending on the platform decimals of milliseconds are shown or not shown.

In first the example, 450 milliseconds elapsed while evaluating (myprog x y z). The second example returns the time for ten evaluations of (myprog x y z). See also date, date-value, time-of-day, and now.

time-of-day

syntax: (time-of-day)

timer

syntax: (timer sym-event-handler | func-event-handler num-seconds [int-option])
syntax: (timer sym-event-handler | func-event-handler)
syntax: (timer)

Starts a one-shot timer firing off the Unix signal SIGALRM, SIGVTALRM, or SIGPROF after the time in seconds (specified in num-seconds) has elapsed. When the timer fires, it calls the user-defined function in sym- or func-event-handler.

On Linux/Unix, an optional 0, 1, or 2 can be specified to control how the timer counts. With default option 0, real time is measured. Option 1 measures the time the CPU spends processing in the process owning the timer. Option 2 is a combination of both called profiling time. See the Unix man page setitimer() for details.

The event handler can start the timer again to achieve a continuous flow of events. Starting with version 8.5.9, seconds can be defined as floating point numbers with a fractional part (e.g., 0.25 for 250 milliseconds).

Defining 0 (zero) as time shuts the running timer down and prevents it from firing.

When called with sym- or func-event-handler, timer returns the elapsed time of the timer in progress. This can be used to program time lines or schedules.

timer called without arguments returns the symbol of the current event handler.

The example shows an event handler, ticker, which starts the timer again after each event.

Note that a timer cannot interrupt an ongoing built-in function. The timer interrupt gets registered by newLISP, but a timer handler cannot run until one expression is evaluated and the next one starts. To interrupt an ongoing I/O operation with timer, use the following pattern, which calls net-select to test if a socket is ready for reading:

In this example, the until loop will run until something can be read from socket, or until ten seconds have passed and the timeout variable is set.

title-case utf8

syntax: (title-case str [bool])

Returns a copy of the string in str with the first character converted to uppercase. When the optional bool parameter evaluates to any value other than nil, the rest of the string is converted to lowercase.

trace

syntax: (trace int-device)
syntax: (trace true)
syntax: (trace nil)
syntax: (trace)

In the first syntax the parameter is an integer of a device like an opened file. Output is continuously written to that device. If int-device is 1 output is written to stdout.

In the second syntax debugger mode is switched on when the parameter evaluates true. When in debugging mode newLISP will stop after each entry and exit from an expression and wait for user input. Highlighting is done by bracketing the expression between two # (number sign) characters. This can be changed to a different character using trace-highlight.:

At the prompt, an s, n, c, or q can be entered to step into or merely execute the next expression. Any expression can be entered at the prompt for evaluation. Entering the name of a variable, for example, would evaluate to its contents. In this way, a variable's contents can be checked during debugging or set to different values.

To set break points where newLISP should interrupt normal execution and go into debugging mode, put (trace true) statements into the newLISP code where execution should switch on the debugger.

In the third syntax (trace nil) closes debugger mode or the trace file opened.

trace-highlight

syntax: (trace-highlight str-pre str-post [str-header str-footer])

Sets the characters or string of characters used to enclose expressions during trace. By default, the # (number sign) is used to enclose the expression highlighted in trace mode. This can be changed to different characters or strings of up to seven characters. If the console window accepts terminal control characters, this can be used to display the expression in a different color, bold, reverse, and so forth.

Two more strings can optionally be specified for str-header and str-footer, which control the separator and prompt. A maximum of 15 characters is allowed for the header and 31 for the footer.

The first example replaces the default # (number sign) with a >> and <<. The second example works on most Linux shells. It may not, however, work in console windows under MS Windows or CYGWIN, depending on the configuration of the terminal.

transpose

syntax: (transpose matrix)

Transposes a matrix by reversing the rows and columns. Any kind of list-matrix can be transposed. Matrices are made rectangular by filling in nil for missing elements, omitting elements where appropriate, or expanding atoms in rows into lists. Matrix dimensions are calculated using the number of rows in the original matrix for columns and the number of elements in the first row as number of rows for the transposed matrix.

The dimensions of a matrix are defined by the number of rows and the number of elements in the first row. A matrix can either be a nested list or an array.

The number of columns in a matrix is defined by the number of elements in the first row of the matrix. If other rows have fewer elements, transpose will assume nil for those missing elements. Superfluous elements in a row will be ignored.

If a row is any other data type besides a list, the transposition treats it like an entire row of elements of that data type:

trim utf8

syntax: (trim str)
syntax: (trim str str-char)
syntax: (trim str str-left-char str-right-char)

Using the first syntax, all white-space characters are trimmed from both sides of str.

The second syntax trims the string str from both sides, stripping the leading and trailing characters as given in str-char. If str-char contains no character, the space character is assumed. trim returns the new string.

The third syntax can either trim different characters from both sides or trim only one side if an empty string is specified for the other.

For more complex cases replace can be used. When possible, the much faster trim is preferred.

true?

syntax: (true? exp)

If the expression in exp evaluates to anything other than nil or the empty list (), true? returns true; otherwise, it returns nil.

unicode

syntax: (unicode str-utf8)

Converts ASCII/UTF-8 character strings in str to UCS-4–encoded Unicode of 4-byte integers per character. The string is terminated with a 4-byte integer 0. This function is only available on UTF-8–enabled versions of newLISP.

On big endian CPU architectures, the byte order will be reversed from high to low. The unicode and utf8 functions are the inverse of each other. These functions are only necessary if UCS-4 Unicode is in use. Most systems use UTF-8 encoding only.

unify

syntax: (unify exp-1 exp-2 [list-env])

Evaluates and matches exp-1 and exp-2. Expressions match if they are equal or if one of the expressions is an unbound variable (which would then be bound to the other expression). If expressions are lists, they are matched by comparing subexpressions. Unbound variables start with an uppercase character to distinguish them from symbols. unify returns nil when the unification process fails, or it returns a list of variable associations on success. When no variables were bound, but the match is still successful, unify returns an empty list. newLISP uses a modified J. Alan Robinson unification algorithm with correctly applied occurs check. See also Peter Norvig's paper about a common unification algorithm bug, which is not present in this implementation.

Since version 10.4.0 the underscore symbol _ (ASCII 95) matches any atom, list or unbound variable and never binds.

unify can take an optional binding or association list in list-env. This is useful when chaining unify expressions and the results of previous unify bindings must be included:

In the previous example, X was bound to 123 earlier and is included in the second statement to pre-bind X.

Use unify with expand

Note that variables are not actually bound as a newLISP assignment. Rather, an association list is returned showing the logical binding. A special syntax of expand can be used to actually replace bound variables with their terms:

Use unify with bind for de-structuring

Model propositional logic with unify

The following example shows how propositional logic can be modeled using unify and expand:

The following is a more complex example showing a small, working PROLOG (Programming in Logic) implementation.

The program handles a database of facts and a database of simple A is a fact if B is a fact rules. A fact is proven true if it either can be found in the facts database or if it can be proven using a rule. Rules can be nested: for example, to prove that somebody (knows physics), it must be proved true that somebody is a physicist. But somebody is only a physicist if that person studied physics. The <- symbol separating the left and right terms of the rules is not required and is only added to make the rules database more readable.

This implementation does not handle multiple terms in the right premise part of the rules, but it does handle backtracking of the rules database to try out different matches. It does not handle backtracking in multiple premises of the rule. For example, if in the following rule A if B and C and D, the premises B and C succeed and D fails, a backtracking mechanism might need to go back and reunify the B or A terms with different facts or rules to make D succeed.

The above algorithm could be written differently by omitting expand from the definition of prove-rule and by passing the environment, e, as an argument to the unify and query functions.

A learning of proven facts can be implemented by appending them to the facts database once they are proven. This would speed up subsequent queries.

Larger PROLOG implementations also allow the evaluation of terms in rules. This makes it possible to implement functions for doing other work while processing rule terms. prove-rule could accomplish this testing for the symbol eval in each rule term.

union

syntax: (union list-1 list-2 [list-3 ... ])

union returns a unique collection list of distinct elements found in two or more lists.

Like the other set functions difference, intersect and unique, union maintains the order of elements as found in the original lists.

unique

syntax: (unique list)

Note that the list does not need to be sorted, but a sorted list makes unique perform faster.

unless

syntax: (unless exp-condition body)

The statements in body are only evaluated if exp-condition evaluates to nil or the empty list (). The result of the last expression in body is returned or nil or the empty list () if body was not executed.

Because unless does not have an else condition as in if, the statements in body need not to be grouped with begin:

unpack ⚠

syntax: (unpack str-format str-addr-packed)
syntax: (unpack str-format num-addr-packed)

syntax: (unpack struct num-addr-packed)
syntax: (unpack struct str-addr-packed)

When the first parameter is a string, unpack unpacks a binary structure in str-addr-packed or pointed to by num-addr-packed into newLISP variables using the format in str-format. unpack is the reverse operation of pack. Using num-addr-packed facilitates the unpacking of structures returned from imported, shared library functions.

If the number specified in num-addr-packed is not a valid memory address, a system bus error or segfault can occur and crash newLISP or leave it in an unstable state.

When the first parameter is the symbol of a struct definition, unpack uses the format as specified in struct. While unpack with str-format literally unpacks as specified, unpack with struct will skip structure aligning pad-bytes depending on data type, order of elements and CPU architecture. Refer to the description of the struct function for more detail.

When unpacking structures containing NULL pointers, an error will be thrown when unpack tries to convert the pointer to a string. If NULL pointers are to be expected, void* should be used in the structure definition.

The > and < specifiers can be used to switch between little endian and big endian byte order when packing or unpacking:

Switching the byte order will affect all number formats with 16-, 32-, or 64-bit sizes.

The pack and unpack format need not be the same, as in the following example:

The examples show spaces between the format specifiers. Although not required, they can improve readability.

If the buffer's size at a memory address is smaller than the formatting string specifies, some formatting characters may be left unused.

until

syntax: (until exp-condition [body])

Evaluates the condition in exp-condition. If the result is nil or the empty list (), the expressions in body are evaluated. Evaluation is repeated until the exp-condition results in a value other than nil or the empty list. The result of the last expression evaluated in body is the return value of the until expression. If body is empty, the result of last exp-condition is returned. until works like (while (not …)).

Use the do-until function to test the condition after evaluation of the body expressions.

upper-case utf8

syntax: (upper-case str)

Returns a copy of the string in str converted to uppercase. International characters are converted correctly.

utf8

syntax: (utf8 str-unicode)

Converts a UCS-4, 4-byte, Unicode-encoded string (str) into UTF-8. This function is only available on UTF-8–enabled versions of newLISP.

The utf8 function can also be used to test for the presence of UTF-8–enabled newLISP:

On big endian CPU architectures, the byte order will be reversed from highest to lowest. The utf8 and unicode functions are the inverse of each other. These functions are only necessary if UCS-4 Unicode is in use. Most systems use UTF-8 Unicode encoding only.

utf8len

syntax: (utf8len str)

Returns the number of characters in a UTF-8–encoded string. UTF-8 characters can be encoded in more than one 8-bit byte. utf8len returns the number of UTF-8 characters in a string. This function is only available on UTF-8–enabled versions of newLISP.

uuid

syntax: (uuid [str-node])

Constructs and returns a UUID (Universally Unique IDentifier). Without a node spec in str-node, a type 4 UUID random generated byte number is returned. When the optional str-node parameter is used, a type 1 UUID is returned. The string in str-node specifies a valid MAC (Media Access Code) from a network adapter installed on the node or a random node ID. When a random node ID is specified, the least significant bit of the first node byte should be set to 1 to avoid clashes with real MAC identifiers. UUIDs of type 1 with node ID are generated from a timestamp and other data. See RFC 4122 for details on UUID generation.

Each invocation of the uuid function will yield a new unique UUID. The UUIDs are generated without system-wide shared stable store (see RFC 4122). If the system generating the UUIDs is distributed over several nodes, then type 1 generation should be used with a different node ID on each node. For several processes on the same node, valid UUIDs are guaranteed even if requested at the same time. This is because the process ID of the generating newLISP process is part of the seed for the random number generator. When type 4 IDs are used on a distributed system, two identical UUID's are still highly unlikely and impossible for type 1 IDs if real MAC addresses are used.

wait-pid

syntax: (wait-pid int-pid [int-options | nil])

Waits for a child process specified in int-pid to end. The child process was previously started with process or fork. When the child process specified in int-pid ends, a list of pid and status value is returned. The status value describes the reason for termination of the child process. The interpretation of the returned status value differs between Linux and other flavors of Unix. Consult the Linux/Unix man pages for the waitpid command (without the hyphen used in newLISP) for further information.

When -1 is specified for int-pid, pid and status information of any child process started by the parent are returned. When 0 is specified, wait-pid only watches child processes in the same process group as the calling process. Any other negative value for int-pid reports child processes in the same process group as specified with a negative sign in int-pid.

An option can be specified in int-option. See Linux/Unix documentation for details on integer values for int-options. As an alternative, nil can be specified. This option causes wait-pid to be non-blocking, returning right away with a 0 in the pid of the list returned. This option used together with an int-pid parameter of -1 can be used to continuously loop and act on returned child processes.

This function is only available on Mac OS X, Linux and other Unix-like operating systems.

The process my-process is started, then the main program blocks in the wait-pid call until my-process has finished.

when

syntax: (when exp-condition body)

The statements in body are only evaluated if exp-condition evaluates to anything not nil and not the empty list (). The result of the last expression in body is returned or nil or the empty list () if body was not executed.

Because when does not have an else condition as in if, the statements in body need not to be grouped with begin:

while

syntax: (while exp-condition body)

Evaluates the condition in exp-condition. If the result is not nil or the empty list (), the expressions in body are evaluated. Evaluation is repeated until an exp-condition results in nil or the empty list (). The result of the body's last evaluated expression is the return value of the while expression.

Use the do-while function to evaluate the condition after evaluating the body of expressions.

write !

syntax: (write)
syntax: (write int-file str-buffer [int-size])
syntax: (write str str-buffer [int-size])

In the second syntax write writes int-size bytes from a buffer in str-buffer to a file specified in int-file, previously obtained from a file open operation. If int-size is not specified, all data in sym-buffer or str-buffer is written. write returns the number of bytes written or nil on failure.

If all parameters are omitted, write writes the contents from the last read-line to standard out (STDOUT).

write is a shorter writing of write-buffer. The longer form still works but is deprecated and should be avoided in new code.

The code in the example writes 100 bytes to the file myfile.ext from the contents in data.

write-char

syntax: (write-char int-file int-byte1 [int-byte2 ... ])

Writes a byte specified in int-byte to a file specified by the file handle in int-file. The file handle is obtained from a previous open operation. Each write-char advances the file pointer by one 8-bit byte.

Use the print and device functions to write larger portions of data at a time. Note that newLISP already supplies a faster built-in function called copy-file.

write-file

syntax: (write-file str-file-name str-buffer)

Writes a file in str-file-name with contents in str-buffer in one swoop and returns the number of bytes written.

On failure the function returns nil. For error information, use sys-error when used on files. When used on URLs net-error gives more error information.

The file myfile is read, encrypted using the password secret, and written back into the new file myfile.enc in the current directory.

write-file can take an http:// or file:// URL in str-file-name. When the prefix http:// is used, write-file works exactly like put-url and can take the same additional parameters:

The file message.txt is created and written at a remote location, http://asite.com, with the contents of str-buffer. In this mode, write-file can also be used to transfer files to remote newLISP server nodes.

write-line !

syntax: (write-line [int-file [str]])
syntax: (write-line str-out [str]])

The string in str and the line termination character(s) are written to the device specified in int-file. When the string argument is omitted write-line writes the contents of the last read-line to int-file If the first argument is omitted too then it writes to to standard out (STDOUT) or to whatever device is set by device.

The first example opens/creates a file, writes a line to it, and closes the file. The second example shows the usage of write-line without arguments. The contents of init.lsp are written to the console screen.

See also the function write for writing to a device without the line-terminating character.

xfer-event

syntax: (xfer-event sym-event-handler | func-event-handler) syntax: (xfer-event nil)

Registers a function in symbol sym-event-handler or in lambda function func-event-handler to monitor HTTP byte transfers initiated by get-url, post-url or put-url or initiated by file functions which can take URLs like load, save, read-file, write-file and append-file.

E.g. whenever a block of data requested with get-url arrives, the function in sym or func will be called with the number of bytes transferred. Likewise when sending data with post-url or any of the other data sending functions, sym or func will be called with the number of bytes transferred for each block of data transferred.

The computer output is shown in bold. Whenever a block of data is received its byte size is printed. Instead of defining the handler function directory with a lambda function in func, a symbol containing a function definition could have been used:

This can be used to monitor the progress of longer lasting byte transfers in HTTP uploads or downloads.

xml-error

syntax: (xml-error)

Returns a list of error information from the last xml-parse operation; otherwise, returns nil if no error occurred. The first element contains text describing the error, and the second element is a number indicating the last scan position in the source XML text, starting at 0 (zero).

xml-parse

syntax: (xml-parse string-xml [int-options [sym-context [func-callback]]])

Parses a string containing XML 1.0 compliant, well-formed XML. xml-parse does not perform DTD validation. It skips DTDs (Document Type Declarations) and processing instructions. Nodes of type ELEMENT, TEXT, CDATA, and COMMENT are parsed, and a newLISP list structure is returned. When an element node does not have attributes or child nodes, it instead contains an empty list. Attributes are returned as association lists, which can be accessed using assoc. When xml-parse fails due to malformed XML, nil is returned and xml-error can be used to access error information.

Modifying the translation process.

Optionally, the int-options parameter can be specified to suppress whitespace, empty attribute lists, and comments. It can also be used to transform tags from strings into symbols. Another function, xml-type-tags, serves for translating the XML tags. The following option numbers can be used:

Options can be combined by adding the numbers (e.g., 3 would combine the options for suppressing whitespace text tags/info and empty attribute lists).

Parsing without any options:

The TEXT elements containing only whitespace make the output very confusing. As the database in example.xml only contains data, we can suppress whitespace, empty attribute lists and comments with option (+ 1 2 4):

Filtering whitespace TEXT, COMMENT tags, and empty attribute lists:

The resulting output looks much more readable, but it can still be improved by using symbols instead of strings for the tags "FRUIT", "NAME", "COLOR", and "PRICE", as well as by suppressing the XML type tags "ELEMENT" and "TEXT" completely using the xml-type-tags directive.

Suppressing XML type tags with xml-type-tags and translating string tags into symbol tags:

When tags are translated into symbols by using option 8, a context can be specified in sym-context. If no context is specified, all symbols will be created inside the current context.

Specifying nil for the XML type tags TEXT and ELEMENT makes them disappear. At the same time, parentheses of the child node list are removed so that child nodes now appear as members of the list, starting with the tag symbol translated from the string tags "FRUIT", "NAME", etcetera.

Parsing into SXML (S-expressions XML) format:

Using xml-type-tags to suppress all XML-type tags—along with the option numbers 1, 2, 4, 8, and 16—SXML formatted output can be generated:

If the original XML tags contain a namespace part separated by a :, that colon will be translated into a . dot in the resulting newLISP symbol.

Note that using option number 16 causes an @ (at symbol) to be added to attribute lists.

Parsing into a specified context

When parsing XML expressions, XML tags are translated into newLISP symbols, when option 8 is specified. The sym-context option specifies the target context for the symbol creation:

If the context does not exist, it will be created. If it exists, the quote can be omitted or the context can be referred to by a variable.

Using a call back function

Normally, xml-parse will not return until all parsing has finished. Using the func-callback option, xml-parse will call back after each tag closing with the generated S-expression and a start position and length in the source XML:

The example callback handler function filters the tags of interest and processes them as they occur.

xml-type-tags

syntax: (xml-type-tags [exp-text-tag exp-cdata-tag exp-comment-tag exp-element-tags])

Can suppress completely or replace the XML type tags "TEXT", "CDATA", "COMMENT", and "ELEMENT" with something else specified in the parameters.

Note that xml-type-tags only suppresses or translates the tags themselves but does not suppress or modify the tagged information. The latter would be done using option numbers in xml-parse.

The first example just shows the currently used type tags. The second example specifies suppression of the "TEXT" and "ELEMENT" tags and shows cdata and !-- instead of "CDATA" and "COMMENT".

zero? bigint

syntax: (zero? exp)

Error codes

TCP/IP and UDP Error Codes

System Symbols and Constants

Variables changed by the system

newLISP maintains several internal symbol variables. All of them are global and can be used by the programmer. Some have write protection, others are user settable. Some will change when used in a sub-expression of the enclosing expression using it. Others are safe when using reentrant in nested functions or expressions.

All symbols starting with the $ character will not be serialized when using the save or source functions.

Predefined variables and functions.

These are preset symbol constants. Two of them are used as namespace templates, one two write platform independent code.

These symbols are not protected and can be redefined by the user. The $x variable is built-in and protected against deletion. This $x variable is also used in curry expressions.

GNU Free Documentation License

Version 1.2, November 2002

Copyright (C) 2000,2001,2002 Free Software Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.

0. PREAMBLE

The purpose of this License is to make a manual, textbook, or other functional and useful document "free" in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.

This License is a kind of "copyleft", which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software.

We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference.

1. APPLICABILITY AND DEFINITIONS

This License applies to any manual or other work, in any medium, that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. Such a notice grants a world-wide, royalty-free license, unlimited in duration, to use that work under the conditions stated herein. The "Document", below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as "you". You accept the license if you copy, modify or distribute the work in a way requiring permission under copyright law.

A "Modified Version" of the Document means any work containing the Document or a portion of it, either copied verbatim, or with modifications and/or translated into another language.

A "Secondary Section" is a named appendix or a front-matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document's overall subject (or to related matters) and contains nothing that could fall directly within that overall subject. (Thus, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any mathematics.) The relationship could be a matter of historical connection with the subject or with related matters, or of legal, commercial, philosophical, ethical or political position regarding them.

The "Invariant Sections" are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released under this License. If a section does not fit the above definition of Secondary then it is not allowed to be designated as Invariant. The Document may contain zero Invariant Sections. If the Document does not identify any Invariant Sections then there are none.

The "Cover Texts" are certain short passages of text that are listed, as Front-Cover Texts or Back-Cover Texts, in the notice that says that the Document is released under this License. A Front-Cover Text may be at most 5 words, and a Back-Cover Text may be at most 25 words.

A "Transparent" copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, that is suitable for revising the document straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent file format whose markup, or absence of markup, has been arranged to thwart or discourage subsequent modification by readers is not Transparent. An image format is not Transparent if used for any substantial amount of text. A copy that is not "Transparent" is called "Opaque".

Examples of suitable formats for Transparent copies include plain ASCII without markup, Texinfo input format, LaTeX input format, SGML or XML using a publicly available DTD, and standard-conforming simple HTML, PostScript or PDF designed for human modification. Examples of transparent image formats include PNG, XCF and JPG. Opaque formats include proprietary formats that can be read and edited only by proprietary word processors, SGML or XML for which the DTD and/or processing tools are not generally available, and the machine-generated HTML, PostScript or PDF produced by some word processors for output purposes only.

The "Title Page" means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, "Title Page" means the text near the most prominent appearance of the work's title, preceding the beginning of the body of the text.

A section "Entitled XYZ" means a named subunit of the Document whose title either is precisely XYZ or contains XYZ in parentheses following text that translates XYZ in another language. (Here XYZ stands for a specific section name mentioned below, such as "Acknowledgements", "Dedications", "Endorsements", or "History".) To "Preserve the Title" of such a section when you modify the Document means that it remains a section "Entitled XYZ" according to this definition.

The Document may include Warranty Disclaimers next to the notice which states that this License applies to the Document. These Warranty Disclaimers are considered to be included by reference in this License, but only as regards disclaiming warranties: any other implication that these Warranty Disclaimers may have is void and has no effect on the meaning of this License.

2. VERBATIM COPYING

You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3.

You may also lend copies, under the same conditions stated above, and you may publicly display copies.

3. COPYING IN QUANTITY

If you publish printed copies (or copies in media that commonly have printed covers) of the Document, numbering more than 100, and the Document's license notice requires Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition. Copying with changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects.

If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages.

If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a computer-network location from which the general network-using public has access to download using public-standard network protocols a complete Transparent copy of the Document, free of added material. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public.

It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document.

4. MODIFICATIONS

You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version:

A. Use in the Title Page (and on the covers, if any) a title distinct from that of the Document, and from those of previous versions (which should, if there were any, be listed in the History section of the Document). You may use the same title as a previous version if the original publisher of that version gives permission.

B. List on the Title Page, as authors, one or more persons or entities responsible for authorship of the modifications in the Modified Version, together with at least five of the principal authors of the Document (all of its principal authors, if it has fewer than five), unless they release you from this requirement.

C. State on the Title page the name of the publisher of the Modified Version, as the publisher.

D. Preserve all the copyright notices of the Document.

E. Add an appropriate copyright notice for your modifications adjacent to the other copyright notices.

F. Include, immediately after the copyright notices, a license notice giving the public permission to use the Modified Version under the terms of this License, in the form shown in the Addendum below.

G. Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document's license notice.

H. Include an unaltered copy of this License.

I. Preserve the section Entitled "History", Preserve its Title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no section Entitled "History" in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous sentence.

J. Preserve the network location, if any, given in the Document for public access to a Transparent copy of the Document, and likewise the network locations given in the Document for previous versions it was based on. These may be placed in the "History" section. You may omit a network location for a work that was published at least four years before the Document itself, or if the original publisher of the version it refers to gives permission.

K. For any section Entitled "Acknowledgements" or "Dedications", Preserve the Title of the section, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein.

L. Preserve all the Invariant Sections of the Document, unaltered in their text and in their titles. Section numbers or the equivalent are not considered part of the section titles.

M. Delete any section Entitled "Endorsements". Such a section may not be included in the Modified Version.

N. Do not retitle any existing section to be Entitled "Endorsements" or to conflict in title with any Invariant Section.

O. Preserve any Warranty Disclaimers.

If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version's license notice. These titles must be distinct from any other section titles.

You may add a section Entitled "Endorsements", provided it contains nothing but endorsements of your Modified Version by various parties--for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard.

You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one.

The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version.

5. COMBINING DOCUMENTS

You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice, and that you preserve all their Warranty Disclaimers.

The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work.

In the combination, you must combine any sections Entitled "History" in the various original documents, forming one section Entitled "History"; likewise combine any sections Entitled "Acknowledgements", and any sections Entitled "Dedications". You must delete all sections Entitled "Endorsements."

6. COLLECTIONS OF DOCUMENTS

You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects.

You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document.

7. AGGREGATION WITH INDEPENDENT WORKS

A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, is called an "aggregate" if the copyright resulting from the compilation is not used to limit the legal rights of the compilation's users beyond what the individual works permit. When the Document is included in an aggregate, this License does not apply to the other works in the aggregate which are not themselves derivative works of the Document.

If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one half of the entire aggregate, the Document's Cover Texts may be placed on covers that bracket the Document within the aggregate, or the electronic equivalent of covers if the Document is in electronic form. Otherwise they must appear on printed covers that bracket the whole aggregate.

8. TRANSLATION

Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4. Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License, and all the license notices in the Document, and any Warranty Disclaimers, provided that you also include the original English version of this License and the original versions of those notices and disclaimers. In case of a disagreement between the translation and the original version of this License or a notice or disclaimer, the original version will prevail.

If a section in the Document is Entitled "Acknowledgements", "Dedications", or "History", the requirement (section 4) to Preserve its Title (section 1) will typically require changing the actual title.

9. TERMINATION

You may not copy, modify, sublicense, or distribute the Document except as expressly provided for under this License. Any other attempt to copy, modify, sublicense or distribute the Document is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance.

10. FUTURE REVISIONS OF THIS LICENSE

The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See http://www.gnu.org/copyleft/.

Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License "or any later version" applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation.

GNU GENERAL PUBLIC LICENSE

Version 3, 29 June 2007

Preamble

The GNU General Public License is a free, copyleft license for software and other kinds of works.

The licenses for most software and other practical works are designed to take away your freedom to share and change the works. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change all versions of a program--to make sure it remains free software for all its users. We, the Free Software Foundation, use the GNU General Public License for most of our software; it applies also to any other work released this way by its authors. You can apply it to your programs, too.

When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for them if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs, and that you know you can do these things.

To protect your rights, we need to prevent others from denying you these rights or asking you to surrender the rights. Therefore, you have certain responsibilities if you distribute copies of the software, or if you modify it: responsibilities to respect the freedom of others.

For example, if you distribute copies of such a program, whether gratis or for a fee, you must pass on to the recipients the same freedoms that you received. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights.

Developers that use the GNU GPL protect your rights with two steps:

(1) assert copyright on the software, and (2) offer you this License giving you legal permission to copy, distribute and/or modify it.

For the developers' and authors' protection, the GPL clearly explains that there is no warranty for this free software. For both users' and authors' sake, the GPL requires that modified versions be marked as changed, so that their problems will not be attributed erroneously to authors of previous versions.

Some devices are designed to deny users access to install or run modified versions of the software inside them, although the manufacturer can do so. This is fundamentally incompatible with the aim of protecting users' freedom to change the software. The systematic pattern of such abuse occurs in the area of products for individuals to use, which is precisely where it is most unacceptable. Therefore, we have designed this version of the GPL to prohibit the practice for those products. If such problems arise substantially in other domains, we stand ready to extend this provision to those domains in future versions of the GPL, as needed to protect the freedom of users.

Finally, every program is threatened constantly by software patents. States should not allow patents to restrict development and use of software on general-purpose computers, but in those that do, we wish to avoid the special danger that patents applied to a free program could make it effectively proprietary. To prevent this, the GPL assures that patents cannot be used to render the program non-free.

The precise terms and conditions for copying, distribution and modification follow.

TERMS AND CONDITIONS

0. Definitions.

"This License" refers to version 3 of the GNU General Public License.

"Copyright" also means copyright-like laws that apply to other kinds of works, such as semiconductor masks.

"The Program" refers to any copyrightable work licensed under this License. Each licensee is addressed as "you". "Licensees" and "recipients" may be individuals or organizations.

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7. Additional Terms.

"Additional permissions" are terms that supplement the terms of this License by making exceptions from one or more of its conditions. Additional permissions that are applicable to the entire Program shall be treated as though they were included in this License, to the extent that they are valid under applicable law. If additional permissions apply only to part of the Program, that part may be used separately under those permissions, but the entire Program remains governed by this License without regard to the additional permissions.

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If conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot convey a covered work so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not convey it at all. For example, if you agree to terms that obligate you to collect a royalty for further conveying from those to whom you convey the Program, the only way you could satisfy both those terms and this License would be to refrain entirely from conveying the Program.

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Notwithstanding any other provision of this License, you have permission to link or combine any covered work with a work licensed under version 3 of the GNU Affero General Public License into a single combined work, and to convey the resulting work. The terms of this License will continue to apply to the part which is the covered work, but the special requirements of the GNU Affero General Public License, section 13, concerning interaction through a network will apply to the combination as such.

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The Free Software Foundation may publish revised and/or new versions of the GNU General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns.

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THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.

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IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

17. Interpretation of Sections 15 and 16.

If the disclaimer of warranty and limitation of liability provided above cannot be given local legal effect according to their terms, reviewing courts shall apply local law that most closely approximates an absolute waiver of all civil liability in connection with the Program, unless a warranty or assumption of liability accompanies a copy of the Program in return for a fee.

<<, >>	bit shift left, bit shift right
&	bitwise and
\|	bitwise inclusive or
^	bitwise exclusive or
~	bitwise not

!	shells out to the operating system
abort	aborts a child process started with `spawn`
destroy	destroys a process created with `fork` or `process`
exec	runs a process, then reads from or writes to it
fork	launches a newLISP child process
pipe	creates a pipe for interprocess communication
process	launches a child process, remapping standard I/O and standard error
receive	receive a message from another process
semaphore	creates and controls semaphores
send	send a message to another process
share	shares memory with other processes
spawn	launches a child process for Cilk process management
sync	waits for child processes launched with `spawn` and collects results
wait-pid	waits for a child process to end

$	accesses system variables $0 -> $15
callback	registers a callback function for an imported library
catch	evaluates an expression, catching errors and early returns
context	creates or switches to a different namespace
copy	copies the result of an evaluation
debug	debugs a user-defined function
delete	deletes symbols from the symbol table
default	returns the contents of a default functor from a context
env	gets or sets the operating system's environment
exit	exits newLISP, setting the exit value
global	makes a symbol accessible outside MAIN
import	imports a function from a shared library
main-args	gets command-line arguments
new	creates a copy of a context
pretty-print	changes the pretty-printing characteristics
read-expr	translates a string to an s-expression without evaluating it
reset	goes to the top level
signal	sets a signal handler
sleep	suspends processing for specified milliseconds
sym	creates a symbol from a string
symbols	returns a list of all symbols in the system
throw	causes a previous catch to return
throw-error	throws a user-defined error
timer	starts a one-shot timer, firing an event
trace	sets or inquires about trace mode
trace-highlight	sets highlighting strings in trace mode

i	for PCRE_CASELESS
m	for PCRE_MULTILINE
s	for PCRE_DOTALL
x	for PCRE_EXTENDED

+, -, *, /, %	integer arithmetic
++	increment integer numbers
--	decrement integer numbers
<, >, =	compares any data type: less, greater, equal
<=, >=, !=	compares any data type: less-equal, greater-equal, not-equal
:	constructs a context symbol and applies it to an object
and	logical `and`
append	appends lists ,arrays or strings to form a new list, array or string
apply	applies a function or primitive to a list of arguments
args	retrieves the argument list of a function or macro expression
assoc	searches for keyword associations in a list
begin	begins a block of functions
bigint	convert a number to big integer format
bind	binds variable associations in a list
case	branches depending on contents of control variable
catch	evaluates an expression, possibly catching errors
chop	chops elements from the end of a list
clean	cleans elements from a list
collect	repeat evaluating an expression and collect results in a list
cond	branches conditionally to expressions
cons	prepends an element to a list, making a new list
constant	defines a constant symbol
count	counts elements of one list that occur in another list
curry	transforms a function f(x, y) into a function fx(y)
define	defines a new function or lambda expression
define-macro	defines a macro or lambda-macro expression
def-new	copies a symbol to a different context (namespace)
difference	returns the difference between two lists
doargs	iterates through the arguments of a function
dolist	evaluates once for each element in a list
dostring	evaluates once for each character in a string
dotimes	evaluates once for each number in a range
dotree	iterates through the symbols of a context
do-until	repeats evaluation of an expression until the condition is met
do-while	repeats evaluation of an expression while the condition is true
dup	duplicates a list or string a specified number of times
ends-with	checks the end of a string or list against a key of the same type
eval	evaluates an expression
exists	checks for the existence of a condition in a list
expand	replaces a symbol in a nested list
explode	explodes a list or string
extend	extends a list or string
first	gets the first element of a list or string
filter	filters a list
find	searches for an element in a list or string
flat	returns the flattened list
fn	defines a new function or lambda expression
for	evaluates once for each number in a range
for-all	checks if all elements in a list meet a condition
if	evaluates an expression conditionally
index	filters elements from a list and returns their indices
intersect	returns the intersection of two lists
lambda	defines a new function or lambda expression
last	returns the last element of a list or string
length	calculates the length of a list or string
let	declares and initializes local variables
letex	expands local variables into an expression, then evaluates
letn	initializes local variables incrementally, like nested lets
list	makes a list
local	declares local variables
lookup	looks up members in an association list
map	maps a function over members of a list, collecting the results
match	matches patterns against lists; for matching against strings, see find and regex
member	finds a member of a list or string
not	logical `not`
nth	gets the nth element of a list or string
or	logical `or`
pop	deletes and returns an element from a list or string
pop-assoc	removes an association from an association list
push	inserts a new element into a list or string
quote	quotes an expression
ref	returns the position of an element inside a nested list
ref-all	returns a list of index vectors of elements inside a nested list
rest	returns all but the first element of a list or string
replace	replaces elements inside a list or string
reverse	reverses a list or string
rotate	rotates a list or string
select	selects and permutes elements from a list or string
self	Accesses the target object inside a FOOP method
set	sets the binding or contents of a symbol
setf setq	sets contents of a symbol or list, array or string reference
set-ref	searches for an element in a nested list and replaces it
set-ref-all	searches for an element in a nested list and replaces all instances
silent	works like begin but suppresses console output of the return value
slice	extracts a sublist or substring
sort	sorts the members of a list
starts-with	checks the beginning of a string or list against a key of the same type
swap	swaps two elements inside a list or string
unify	unifies two expressions
unique	returns a list without duplicates
union	returns a unique list of elements found in two or more lists.
unless	evaluates an expression conditionally
until	repeats evaluation of an expression until the condition is met
when	evaluates a block of statements conditionally
while	repeats evaluation of an expression while the condition is true

address	gets the memory address of a number or string
bigint	convert a number to big integer format
bits	translates a number into binary representation
char	translates between characters and ASCII codes
chop	chops off characters from the end of a string
dostring	evaluates once for each character in a string
dup	duplicates a list or string a specified number of times
ends-with	checks the end of a string or list against a key of the same type
encrypt	does a one-time–pad encryption and decryption of a string
eval-string	compiles, then evaluates a string
explode	transforms a string into a list of characters
extend	extends a list or string
find	searches for an element in a list or string
find-all	returns a list of all pattern matches found in string
first	gets the first element in a list or string
float	translates a string or integer into a floating point number
format	formats numbers and strings as in the C language
get-char	gets a character from a memory address
get-float	gets a double float from a memory address
get-int	gets a 32-bit integer from a memory address
get-long	gets a long 64-bit integer from a memory address
get-string	gets a string from a memory address
int	translates a string or float into an integer
join	joins a list of strings
last	returns the last element of a list or string
lower-case	converts a string to lowercase characters
member	finds a list or string member
name	returns the name of a symbol or its context as a string
nth	gets the nth element in a list or string
pack	packs newLISP expressions into a binary structure
parse	breaks a string into tokens
pop	pops from a string
push	pushes onto a string
regex	performs a Perl-compatible regular expression search
regex-comp	pre-compiles a regular expression pattern
replace	replaces elements in a list or string
rest	gets all but the first element of a list or string
reverse	reverses a list or string
rotate	rotates a list or string
select	selects and permutes elements from a list or string
setf setq	sets contents of a string reference
slice	extracts a substring or sublist
source	returns the source required to bind a symbol as a string
starts-with	checks the start of the string or list against a key string or list
string	transforms anything into a string
sym	translates a string into a symbol
title-case	converts the first character of a string to uppercase
trim	trims a string on one or both sides
unicode	converts ASCII or UTF-8 to UCS-4 Unicode
utf8	converts UCS-4 Unicode to UTF-8
utf8len	returns length of an UTF-8 string in UTF-8 characters
unpack	unpacks a binary structure into newLISP expressions
upper-case	converts a string to uppercase characters

abs	returns the absolute value of a number
acos	calculates the arc-cosine of a number
acosh	calculates the inverse hyperbolic cosine of a number
add	adds floating point or integer numbers and returns a floating point number
array	creates an array
array-list	returns a list conversion from an array
asin	calculates the arcsine of a number
asinh	calculates the inverse hyperbolic sine of a number
atan	calculates the arctangent of a number
atanh	calculates the inverse hyperbolic tangent of a number
atan2	computes the principal value of the arctangent of Y / X in radians
beta	calculates the beta function
betai	calculates the incomplete beta function
binomial	calculates the binomial function
ceil	rounds up to the next integer
cos	calculates the cosine of a number
cosh	calculates the hyperbolic cosine of a number
crc32	calculates a 32-bit CRC for a data buffer
dec	decrements a number in a variable, list or array
div	divides floating point or integer numbers
erf	calculates the error function of a number
exp	calculates the exponential e of a number
factor	factors a number into primes
fft	performs a fast Fourier transform (FFT)
floor	rounds down to the next integer
flt	converts a number to a 32-bit integer representing a float
gammai	calculates the incomplete Gamma function
gammaln	calculates the log Gamma function
gcd	calculates the greatest common divisor of a group of integers
ifft	performs an inverse fast Fourier transform (IFFT)
inc	increments a number in a variable, list or array
inf?	checks if a floating point value is infinite
log	calculates the natural or other logarithm of a number
min	finds the smallest value in a series of values
max	finds the largest value in a series of values
mod	calculates the modulo of two numbers
mul	multiplies floating point or integer numbers
NaN?	checks if a float is NaN (not a number)
round	rounds a number
pow	calculates x to the power of y
sequence	generates a list sequence of numbers
series	creates a geometric sequence of numbers
sgn	calculates the signum function of a number
sin	calculates the sine of a number
sinh	calculates the hyperbolic sine of a number
sqrt	calculates the square root of a number
ssq	calculates the sum of squares of a vector
sub	subtracts floating point or integer numbers
tan	calculates the tangent of a number
tanh	calculates the hyperbolic tangent of a number
uuid	returns a UUID (Universal Unique IDentifier)

atom?	checks if an expression is an atom
array?	checks if an expression is an array
bigint?	checks if a number is a big integer
context?	checks if an expression is a context
directory?	checks if a disk node is a directory
empty?	checks if a list or string is empty
even?	checks the parity of an integer number
file?	checks if a file exists
float?	checks if an expression is a float
global?	checks if a symbol is global
inf?	checks if a floating point value is infinite
integer?	checks if an expression is an integer
lambda?	checks if an expression is a lambda expression
legal?	checks if a string contains a legal symbol
list?	checks if an expression is a list
macro?	checks if an expression is a lambda-macro expression
NaN?	checks if a float is NaN (not a number)
nil?	checks if an expression is `nil`
null?	checks if an expression is `nil`, `""`, `()`, `0` or `0.0`
number?	checks if an expression is a float or an integer
odd?	checks the parity of an integer number
protected?	checks if a symbol is protected
primitive?	checks if an expression is a primitive
quote?	checks if an expression is quoted
string?	checks if an expression is a string
symbol?	checks if an expression is a symbol
true?	checks if an expression is not `nil`
zero?	checks if an expression is `0` or `0.0`

date	converts a date-time value to a string
date-list	returns a list of year, month, day, hours, minutes, seconds from a time value in seconds
date-parse	parses a date string and returns the number of seconds passed since January 1, 1970, (formerly `parse-date`)
date-value	calculates the time in seconds since January 1, 1970 for a date and time
now	returns a list of current date-time information
time	calculates the time it takes to evaluate an expression in milliseconds
time-of-day	calculates the number of milliseconds elapsed since the day started

amb	randomly selects an argument and evaluates it
bayes-query	calculates Bayesian probabilities for a data set
bayes-train	counts items in lists for Bayesian or frequency analysis
corr	calculates the product-moment correlation coefficient
crit-chi2	calculates the Chi² statistic for a given probability
crit-f	calculates the F statistic for a given probability
crit-t	calculates the Student's t statistic for a given probability
crit-z	calculates the normal distributed Z for a given probability
kmeans-query	calculates distances to cluster centroids or other data points
kmeans-train	partitions a data set into clusters
normal	makes a list of normal distributed floating point numbers
prob-chi2	calculates the tail probability of a Chi² distribution value
prob-f	calculates the tail probability of a F distribution value
prob-t	calculates the tail probability of a Student's t distribution value
prob-z	calculates the cumulated probability of a Z distribution value
rand	generates random numbers in a range
random	generates a list of evenly distributed floats
randomize	shuffles all of the elements in a list
seed	seeds the internal random number generator
stats	calculates some basic statistics for a data vector
t-test	compares means of data samples using the Student's t statistic

ends-with	tests if a list or string ends with a pattern
find	searches for a pattern in a list or string
find-all	finds all occurrences of a pattern in a string
match	matches list patterns
parse	breaks a string along around patterns
ref	returns the position of an element inside a nested list
ref-all	returns a list of index vectors of elements inside a nested list
regex	finds patterns in a string
replace	replaces patterns in a string
search	searches for a pattern in a file
starts-with	tests if a list or string starts with a pattern
unify	performs a logical unification of patterns

fv	returns the future value of an investment
irr	calculates the internal rate of return
nper	calculates the number of periods for an investment
npv	calculates the net present value of an investment
pv	calculates the present value of an investment
pmt	calculates the payment for a loan

append-file	appends data to a file
close	closes a file
current-line	retrieves contents of last read-line buffer
device	sets or inquires about current print device
exec	launches another program, then reads from or writes to it
load	loads and evaluates a file of newLISP code
open	opens a file for reading or writing
peek	checks file descriptor for number of bytes ready for reading
print	prints to the console or a device
println	prints to the console or a device with a line-feed
read	reads binary data from a file
read-char	reads an 8-bit character from a file
read-file	reads a whole file in one operation
read-key	reads a keyboard key
read-line	reads a line from the console or file
read-utf8	reads UTF-8 character from a file
save	saves a workspace, context, or symbol to a file
search	searches a file for a string
seek	sets or reads a file position
write	writes binary data to a file
write-char	writes a character to a file
write-file	writes a file in one operation
write-line	writes a line to the console or a file

change-dir	changes to a different drive and directory
copy-file	copies a file
delete-file	deletes a file
directory	returns a list of directory entries
file-info	gets file size, date, time, and attributes
make-dir	makes a new directory
real-path	returns the full path of the relative file path
remove-dir	removes an empty directory
rename-file	renames a file or directory

base64-enc	encodes a string into BASE64 format
base64-dec	decodes a string from BASE64 format
delete-url	deletes a file or page from the web
get-url	reads a file or page from the web
json-error	returns error information from a failed JSON translation.
json-parse	parses JSON formatted data
post-url	posts info to a URL address
put-url	uploads a page to a URL address
xfer-event	registers an event handler for HTTP byte transfers
xml-error	returns last XML parse error
xml-parse	parses an XML document
xml-type-tags	shows or modifies XML type tags

net-accept	accepts a new incoming connection
net-close	closes a socket connection
net-connect	connects to a remote host
net-error	returns the last error
net-eval	evaluates expressions on multiple remote newLISP servers
net-interface	Sets the default interface IP address on multihomed computers.
net-ipv	Switches between IPv4 and IPv6 internet protocol versions.
net-listen	listens for connections to a local socket
net-local	returns the local IP and port number for a connection
net-lookup	returns the name for an IP number
net-packet	send a custom configured IP packet over raw sockets
net-peek	returns the number of characters ready to be read from a network socket
net-peer	returns the remote IP and port for a net connect
net-ping	sends a ping packet (ICMP echo request) to one or more addresses
net-receive	reads data on a socket connection
net-receive-from	reads a UDP on an open connection
net-receive-udp	reads a UDP and closes the connection
net-select	checks a socket or list of sockets for status
net-send	sends data on a socket connection
net-send-to	sends a UDP on an open connection
net-send-udp	sends a UDP and closes the connection
net-service	translates a service name into a port number
net-sessions	returns a list of currently open connections

display-html	display an HTML page in a web browser
eval-string-js	evaluate JavaScript in the current web browser page

command-event	pre-processes the command-line and HTTP requests
error-event	defines an error handler
last-error	report the last error number and text
macro	create a reader expansion macro
ostype	contains a string describing the OS platform
prefix	Returns the context prefix of a symbol
prompt-event	customizes the interactive newLISP shell prompt
read-expr	reads and translates s-expressions from source
reader-event	preprocess expressions before evaluation event-driven
set-locale	switches to a different locale
source	returns the source required to bind a symbol to a string
sys-error	reports OS system error numbers
sys-info	gives information about system resources
term	returns the term part of a symbol or its context as a string

address	returns the memory address of a number or string
callback	registers a callback function for an imported library
flt	converts a number to a 32-bit integer representing a float
float	translates a string or integer into a floating point number
get-char	gets a character from a memory address
get-float	gets a double float from a memory address
get-int	gets a 32-bit integer from a memory address
get-long	gets a long 64-bit integer from a memory address
get-string	gets a string from a memory address
import	imports a function from a shared library
int	translates a string or float into an integer
pack	packs newLISP expressions into a binary structure
struct	Defines a data structure with C types
unpack	unpacks a binary structure into newLISP expressions

command-event	pre-processes the command-line and HTTP requests
cpymem	copies memory between addresses
dump	shows memory address and contents of newLISP cells
prompt-event	customizes the interactive newLISP shell prompt
read-expr	reads and translates s-expressions from source
reader-event	preprocess expressions before evaluation event-driven

name	description
mean	mean of data in vector
value	value to compare
sdev	standard deviation in data vector
mean-error	standard error of mean
t	t between mean and value
df	degrees of freedom
p	two tailed probability of t under the null hypothesis

name	description
mean-a	mean of group A
mean-b	mean of group B
sdev-a	standard deviation in group A
sdev-b	standard deviation in group B
t	t between mean values
df	degrees of freedom
p	two tailed probability of t under the null hypothesis

option	description
1	suppress whitespace text tags
2	suppress empty attribute lists
4	suppress comment tags
8	translate string tags into symbols
16	add SXML (S-expression XML) attribute tags (@ ...)

description	no
not enough memory	1
environment stack overflow	2
call stack overflow	3
problem accessing file	4
not an expression	5
missing parenthesis	6
string token too long	7
missing argument	8
number or string expected	9
value expected	10
string expected	11
symbol expected	12
context expected	13
symbol or context expected	14
list expected	15
list or array expected	16
list or symbol expected	17
list or string expected	18
list or number expected	19
array expected	20
array, list or string expected	21
lambda expected	22
lambda-macro expected	23
invalid function	24
invalid lambda expression	25
invalid macro expression	26
invalid let parameter list	27
problem saving file	28
division by zero	29
matrix expected	30
wrong dimensions	31
matrix is singular	32
syntax in regular expression	33
throw without catch	34
problem loading library	35
import function not found	36
symbol is protected	37
error number too high	38
regular expression	39
missing end of text [/text]	40
mismatch in number of arguments	41
problem in format string	42
data type and format don't match	43
invalid parameter	44
invalid parameter: 0.0	45
invalid parameter: NaN	46
invalid UTF8 string	47
illegal parameter type	48
symbol not in MAIN context	49
symbol not in current context	50
target cannot be MAIN	51
list index out of bounds	52
array index out of bounds	53
string index out of bounds	54
nesting level too deep	55
list reference changed	56
invalid syntax	57
user error	58
user reset -	59
received SIGINT -	60
function is not reentrant	61
local symbol is protected	62
no reference found	63
list is empty	64
I/O error	65
working directory not found	66
invalid PID	67
cannot open socket pair	68
cannot fork process	69
no comm channel found	70
ffi preparation failed	71
invalid ffi type	72
ffi struct expected	73
bigint type not applicable	74
not a number or infinite	75
cannot convert NULL to string	76

User Manual and Reference v.10.7.0

Contents

User Manual

Function Reference

Appendix

newLISP User Manual

1. Introduction

newLISP-GS

Licensing

2. Deprecated functions and future changes

3. Interactive Lisp mode

4. Command-line options, startup and directories

Command line help summary

Specifying files as URLs

No loading of init.lsp

Stack size

Maximum memory usage

Direct execution mode

Logging I/O

Specifying the working directory

Suppressing the prompt and HTTP processing

Forcing prompts in pipe I/O mode

newLISP as a TCP/IP server

TCP/IP daemon mode

HTTP-only server mode

Local domain Unix socket server

Connection timeout

inetd daemon mode

Linking a source file with newLISP for a new executable

5. Startup, directories, environment

Environment variable NEWLISPDIR

The initialization file init.lsp

Directories on Linux, BSD, Mac OS X and other Unix

Directories on MS Windows

6. Extending newLISP with shared libraries

7. newLISP as a shared library

newLISP as C library

newLISP as a JavaScript library

8. Evaluating newLISP expressions

Interactive multiline expressions

Integer, floating point data and operators

Big integer, multiple precision arithmetic

Evaluation rules and data types

9. Lambda expressions in newLISP

10. nil, true, cons, and ()

11. Arrays

12. Indexing elements of strings, lists, and arrays

Implicit indexing for nth

Implicit indexing and the default functor

Implicit indexing for rest and slice

Modify references in lists, arrays and strings

13. Destructive versus nondestructive functions

Make a destructive function non-destructive

14. Early return from functions, loops, and blocks

Using catch and throw

Using and and or

15. Dynamic and lexical scoping

16. Contexts

Symbol creation in contexts

Creating contexts

Global scope

Symbol protection

Overwriting global symbols and built-ins

Variables containing contexts

Sequence of creating or loading contexts

Contexts as programming modules

Contexts as data containers

Loading and declaring contexts

Serializing contexts

17. The context default functor

Functions with memory

Hash functions and dictionaries

Passing data by reference

18. Functional object-oriented programming

FOOP classes and constructors

Objects and associations

The colon : operator and polymorphism

Structuring a larger FOOP program

19. Concurrent processing and distributed computing

Cilk API

`inetd` daemon mode

Environment variable `NEWLISPDIR`

The initialization file `init.lsp`

10. `nil`, `true`, `cons`, and `()`

Implicit indexing for `nth`

Implicit indexing for `rest` and `slice`

Using `catch` and `throw`

Using `and` and `or`

The colon `:` operator and polymorphism

syntax: (< exp-1 [exp-2 ... ])
syntax: (> exp-1 [exp-2 ... ])
syntax: (= exp-1 [exp-2 ... ])
syntax: (<= exp-1 [exp-2 ... ])
syntax: (>= exp-1 [exp-2 ... ])
syntax: (!= exp-1 [exp-2 ... ])

syntax: (<< int-1 int-2 [int-3 ... ])
syntax: (>> int-1 int-2 [int-3 ... ])
syntax: (<< int-1)
syntax: (>> int-1)

variable name	purpose	protected	reentrant
`$0 - $15`	Used primarily in regular expressions. `$0` is also used to record the last state or count of execution of some functions.	no	no
`$args`	Contains the list parameters not bound to local variables. Normally the function args is used to retrieve the contents of this variable.	yes	yes
`$count`	The count of elements matching when using find-all, replace, ref-all and set-ref-all or the count of characters processed by read-expr.	yes	no
`$idx`	The function dolist maintains this as a list index or offset. The functions map, series, while, until, do-while and do-until maintain this variable as an iteration counter starting with 0 (zero) for the first iteration.	yes	yes
`$it`	The anaphoric `$it` refers to the result inside an executing expression, i.e. in self referential assignments. `$it` is only available inside the function expression setting it, and is set to `nil` on exit of that expression. The following functions use it: if, hashes, find-all, replace, set-ref, set-ref-all and setf setq.	yes	no
`$main-args`	Contains the list of command line arguments passed by the OS to newLISP when it was started. Normally the function main-args is used to retrieve the contents.	yes	n/a

name	purpose	protected	reentrant
`Class`	Is the predefined general FOOP class constructor which can be used together with `new` to create new FOOP classes, e.g: `(new Class 'Rectangle)` would create a class and object constructor for a user class `Rectangle`. See the FOOP classes and constructors chapter in the users manual for details.	no	n/a
`ostype`	Contains a string identifying the OS-Platform for which the running newLISP version has been compiled. See the reference section for details	yes	n/a
`Tree`	Is a predefined namespace to serve as a hash like dictionary. Instead of writing `(define Foo:Foo)` to create a `Foo` dictionary, the expression `(new Tree 'Foo)` can be used as well. See the chapter Hash functions and dictionaries foe details.	no	n/a
`module`	Is a predefined function to load modules. Instead of using `load` together with the `NEWLISPDIR` environment variable, the `module` function loads automatically from `$NEWLISPDIR/modules/`.	no	n/a