ECL stands for Embeddable Common-Lisp and is a free open source ANSI Common-Lisp implementation. Its distinguishing attributes are maintaining a small-footprint, and being embeddable with existing C/C++ applications. ECL is LGPL licensed and hosted at ecls.sourceforge.net.
ECL-11.1.1 is currently available to MetaARPA members on most SDF hosts.
There are currently two Common-Lisp implementations available on SDF; ECL and CLISP. Both are largely compliant with the ANSI Common-Lisp standard. Each supports various object systems, debugging, bytecode compiling, unicode, sockets, streams, etc. CLISP comes with built-in readline support; ECL doesn't, though it can be added; see the ASDF section. In addition to being smaller and faster than CLISP, ECL can be embedded in C/C++ programs, allow embedded C/C++ code in Lisp programs, and produce stand-alone ELF executables. ECL is also very well documented.
By default ECL starts up in interactive mode. Log into SDF host miku and
type 'ecl'
; you should see something like below:
ECL (Embeddable Common-Lisp) 11.1.1 Copyright (C) 1984 Taiichi Yuasa and Masami Hagiya Copyright (C) 1993 Giuseppe Attardi Copyright (C) 2000 Juan J. Garcia-Ripoll ECL is free software, and you are welcome to redistribute it under certain conditions; see file 'Copyright' for details. Type :h for Help. Top level. >
The default ECL prompt is ">". Enter Common-Lisp commands in the usual way:
> (+ 1 2 3) 6 > (* 4 5) 20 > (format t "hello SDF~&") hello SDF NIL >
In-line help is available ; type :h for options.
The debugger can be entered using (break)
; once entered typed :h to see options.
To exit the ECL interactive session type :exit
.
To use ECL as a script executor (ie. CGI) the -shell and/or -eval options can be used. The -norc is often a good addition so as to avoid unnecessary loading of modules, etc.
ex: hello.lsp
% echo '(format t "~&Hello SDF~&")' > hello.lsp % ecl -norc -script hello.lsp Hello SDF
It's also possible to use ECL to execute simple Common-Lisp one-liners at the command line (note that princ is needed for screen output):
% ecl -norc -shell /dev/null -eval "(princ (* 1 2 3))" 6
A nicer way to accomplish the same is to create a small shell script:
#!/bin/sh # lispit - executes a lisp expression and dumps it to stdout LSP_EXPR=${@} if [ "$#" -eq 0 ]; then echo "lispit - executes a lisp expression" echo " usage: lispit '(lisp_expression)'" echo "" exit 1 fi ecl -norc -shell /dev/null -eval "(princ ${LSP_EXPR} )" echo "" exit 0
Example run:
% lispit '(mapcar (lambda (x) (expt x 2)) `(1 2 3 4 5))' (1 4 9 16 25)
ASDF (Another System Definition Facility) is an extensible build facility for Common-Lisp software. ECL comes with ASDF bundled in, however on SDF, users must setup their own ASDF repository under their $HOME directory.
The following outlines the process, using the ecl-readline module (adds GNU readline support to ECL) as example:
1) Create the user-level ASDF repository:
% mkdir -p $HOME/LISP/ASDF
2) Create the ASDF config directory and config file*:
% cd $HOME % mkdir -p .config/common-lisp/source-registry.conf.d % vi .config/common-lisp/source-registry.conf.d/asdf.conf # ../asdf.conf ;;additional directory for ASDF to search (no recursion): (:directory "/LISP/ASDF/")
*note: you can call the conf file anything you want.
3) Download ecl-readline module and copy select files to $HOME/LISP/ASDF:
% cd /tmp % snarf http://www.common-lisp.net/project/ecl-readline/releases/ecl-readline-0.4.1.tar.gz % tar xzf ecl-readline-0.4.1.tar.gz % cd ecl-readline-0.4.1/ % cp ecl-*.* $HOME/LISP/ASDF/
4) Create the ECL startup file:
# $HOME/.eclrc (require 'asdf) (asdf:operate 'asdf:load-op 'ecl-readline) (ecl-readline::enable)
The next time you startup ECL it will compile the ecl-readline module and launch an interactive session. With ecl-readline enabled the default ECL prompt is "CL-USER[n]>" and you should then be able to use Emacs-style command editing and history recall. If you don't like the provided prompt you can change it by editing the ecl-readline.lisp file.
Additional modifications can be made to the ECL startup file, such as user-defined functions and tweaks to various modules. Below is a more nuanced example which reduces the verbosity at startup, modifies ecl-readline's history file location, and adds an external SHELL function similar to that found in CLISP:
# $HOME/.eclrc (require 'asdf) (setf ASDF:*ASDF-VERBOSE* nil) ; quiets ASDF output some (setf *load-verbose* nil) ; quiets the LOAD process some (asdf:operate 'asdf:load-op 'ecl-readline) (ecl-readline::enable :history-file "/var/tmp/.ecl-history") ;; ;; customizations ;; GNU clisp-like SHELL cmd (defun shell (&optional (shell_cmd "$SHELL")) "Args: (&optional shell_cmd) SHELL calls the EXT:SYSTEM function. Executes SHELL_CMD if given, otherwise User sub-shell is spawned. SHELL_CMD be string or symbol, 256 characters max." (ext:system shell_cmd))