lfe(1)                                                                  lfe(1)



NAME
       lfe - Lisp Flavoured Erlang (LFE) shell

SYNOPSIS
       lfe  is a simple LFE repl (read-eval-print loop) in which you can enter
       sexprs which then are evaluated and the value printed.   You  can  also
       define  local  functions  and  macros as well as set variables.  It can
       read commands either from the standard input or from a file.

       The LFE repl is implemented in the module lfe_shell.

BUILT-IN SHELL FUNCTIONS
       These are defined as normal functions and macros and can be called from
       anywhere  in  the shell.  They can even be redefined.  They can also be
       explicitly called (: lfe_shell ...).

       (c File [Options])

       Compile and load an LFE file.  Assumes default extension .lfe.

       (cd Dir)

       Change the working directory.

       (ec File [Options])

       Compile and load an Erlang file.

       (flush)

       Flush any messages sent to the shell.

       (i)

       Print information about the currently running processes in the system.

       (l Module ...)

       Load modules.

       (m Module ...)

       Print out module information, if no modules are given then print infor‐
       mation about all modules.

       (pid x y z)

       Create a pid from x, y, z.

       (p Expr)

       (pp Expr)

       Print/prettyprint a value to full depth.

       (pwd)

       Print the current working directory.

       (regs)

       Print information about the registered processes in the system.

       (: c Command Arg ...)

       (c:Command Arg ...)

       All  the  commands  in the standard Erlang shell can be reached in this
       way.

BUILT-IN SHELL COMMANDS
       These are special forms which are only recognised at the  top-level  in
       shell input.  The cannot be redefined.

       (reset-environment)

       Resets the environment to its initial state.  This will clear all vari‐
       ables, functions an macros that have been set.

       (set Pattern Expr)

       (set Pattern (when Guard) Expr)

       Evaluate Expr and match the result with Pattern  binding  variables  in
       it.   These variables can then be used in the shell and also rebound in
       another set.

       (slurp File)

       Slurp in a source LFE file and makes all functions and  macros  defined
       in  the file available in the shell.  Only one file can be slurped at a
       time and slurping a new file basically does an unslurp first.

       (unslurp)

       Revert back to the state before the last slurp  removing  all  function
       and macro definitions both in the slurped file and defined in the shell
       since then.

       (run File)

       Execute all the shell commands in File.  All defined  variables,  func‐
       tions  and  macros will be saved in the environment if there are no er‐
       rors.

SHELL FUNCTIONS AND MACROS
       Functions and macros can be defined in the shell.  These will  only  be
       local  to  the  shell and cannot be called from modules.  The forms are
       the standard forms for defining functions and macros.

       (defun Fun ...)

       Define a function in the shell.

       (defmacro Macro ...)

       Define a macro in the shell.

BUILT-IN SHELL VARIABLES
       +, ++, +++

       The three previous expressions input.

       *, **, ***

       The values of the previous 3 expressions.

       -

       The current expression input.

SHELL ENVIRONMENT
       The shell maintains an environment of local function and macro  defini‐
       tions,  and  variable  bindings.  The environment can be accessed using
       the built-in shell variable $ENV.  This  can  be  useful  when  calling
       functions  like macroexpand and macro-function which unless an explicit
       environment is given will only search the default environment.

STARTING THE LFE SHELL
       After installing the best way is probably to start Erlang directly run‐
       ning the LFE shell with:

              lfe [flags]

       From  a normal Erlang shell the best way to start the shell is by call‐
       ing:

              17> lfe_shell:server().

       Giving the user switch commands:

              --> s lfe_shell
              --> c

       will create a job running the LFE shell and connect to it.   This  also
       works when starting a remote shell.

RUNNING LFE SHELL SCRIPTS
       The  LFE  shell  can  also  be directly called to run LFE shell scripts
       with:

              lfe [flags] file [args]

       This will start the shell, run a script with  LFE  shell  commands  and
       then  terminate  the  shell.  The following built-in variables are also
       bound:

       script-name

       The name of the script file as a string.

       script-args

       A list of the arguments to the script as strings.  If no arguments have
       been given then this will be an empty list.

SEE ALSO
       lfescript(1), lfe_guide(7)

AUTHORS
       Robert Virding.



                                   2008-2016                            lfe(1)
