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lfescript(1)							    lfescript(1)

NAME
     lfescript - Lisp Flavoured Erlang (LFE) scripting support

SYNOPSIS
     lfescript provides support for running short LFE programs without having to
     compile them first and an easy way to retrieve the command line arguments.

EXPORTS
     script-name script-arg1 script-arg2 ...

     lfescript lfescript-flags script-name script-arg1 script-arg2 ...

     lfescript runs a script written in LFE.

     lfescript:script_name() -> File

     Types:

	    File = filename()

     The  script_name/0  function  returns  the name of the lfescript being exe-
     cuted.  If the function is invoked outside the context of an lfescript, the
     behavior is undefined.

EXAMPLE
     Here follows an example script.

	    $ cat factorial
	    #! /usr/bin/env lfescript
	    ;; -*- mode: lfe -*-
	    ;;! -smp enable -sname factorial -mnesia debug verbose

	    (defun main
	      ([(list string)]
	       (try
		   (let* ((n (list_to_integer string))
			  (f (fac n)))
		     (lfe_io:format "factorial ~w = ~w\n" (list n f)))
		 (catch
		   ((tuple _ _ _) (usage)))))
	      ([_] (usage)))

	    (defun fac
	      ([0] 1)
	      ([n] (* n (fac (- n 1)))))

	    (defun usage ()
	      (lfe_io:format "usage: factorial integer\n" ()))

     The header of the LFE script is different from a normal  LFE  module.   The
     first  line is an interpreter line which invokes lfescript if the script is
     run as in the first command line above.  If lfescript is explicitly invoked
     in the second command line above then this header line will be ignored.  On
     the second or third line it is possible to give arguments to  the	emulator
     with the syntax:

	    ;;! -smp enable -sname factorial -mnesia debug verbose

     In  the  example  the  second  line is an optional directive to Emacs which
     causes it to enter LFE mode when editing the script file.

     The rest of the file contains LFE source code.  It must always contain  the
     function  main/1.	When the script is run this function will be called with
     a list of strings representing the arguments  with  which	the  script  was
     called.   It  is  possible  to define, include and use macros in the source
     code.

     The source code is checked and warnings and errors  will  be  printed.   If
     there  are  errors  the script will not run and it will terminate with exit
     status 127.  Otherwise the code  will  be	interpreted.   If  the	function
     main/1  returns  successfully then the exit status for the script will be 0
     but if an exception is raised then exit status will be 127.

OPTIONS
     The following option is accepted by lfescript

     * -s - Only perform a syntactic and semantic  check  of  the  script  file.
       Warnings  and errors (if any) are written to the standard output, but the
       script will not be run.	The exit status will be 0 if there were  no  er-
       rors, and 127 otherwise.

     Unrecognised options are ignored.

ENVIRONMENT VARIABLES
     LFESCRIPT_EMULATOR

     The  command  used  to  start the emulator.  Default is `erl'.  This can be
     useful for passing arguments into the emulator, for example

	    LFESCRIPT_EMULATOR="erl -pa sune"

     will add the directory sune to the code path.

SEE ALSO
     lfe(1), lfe_guide(7)

AUTHORS
     Robert Virding.

				    2013-2016			    lfescript(1)

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