Emacs Lisp implementation in JavaScript.

Copyright (c) 2009 Sami Samhuri - sami.samhuri@gmail.com

Released under the terms of the MIT license.  See the included file
LICENSE.

Latest version available on github:

    http://github.com/samsonjs/elisp.js


      Introduction
(or "You must be kidding")
==========================

I'm not 100% sure why I think this might be useful to somebody.  The
idea of editing code directly on github or bitbucket in a web browser
is pretty cool though, and if you're going to do such a thing why not
use the best tools available.  IMO those tools are written in Emacs
Lisp so I would like to use them in the browser.  Maybe with some
HTML5 offline goodness thrown in.

Seeing Ymacs[1] in action[2] was also an inspiration to start this
project as I've had it on my TODO list for several months now.  Emacs
in the browser could be a reality; Ymacs is proof.

[1] http://www.ymacs.org/
[2] http://www.ymacs.org/demo/


Getting Started
===============

Command line
------------

If you have rlwrap and js then just run el.sh.  If not install a
JavaScript shell of your choice, and I recommend you install rlwrap
(readline wrap).  Edit el.sh to reflect whether or not you use rlwrap
and your shell's name or path.  Then run el.sh.  I've only run this
under SpiderMonkey so I have no idea if it works under any other
implementations.  Glad to accept info and/or patches.

Type a 'Q' or 'q' to quit the repl.  Or anything that starts with Q,
like 'quickly quit lisp!'.  (If lisp freaks out because you entered ^D
or something ^C or ^Z should still get you out.)


Emacs
-----

I use Emacs and js-comint.el[3] with inferior-js set to
/opt/local/bin/js, which is SpiderMonkey[4] from MacPorts[5] on Snow
Leopard.

[3] http://js-comint-el.sourceforge.net/
[4] http://www.mozilla.org/js/spidermonkey/
[5] http://www.macports.org/

For loading code C-c b sends the buffer to the JS repl.  I also use
the EL.rep (read-eval-print), EL.parse, EL.eval, and EL.print
functions defined in el/repl.js

Here's an example:

% cd Projects/elisp.js
% rlwrap js
js> load('el.js')
elisp> 
(defvar *directory* "/Users/sjs" "My home directory")
elisp>
*directory*
["string", "/Users/sjs"]
elisp> 
(setq foo 1 bar 2 baz 3)
["number", 3]
elisp> 
(/ (+ foo bar baz) 3)
["number", 2]
elisp> 
(string-match "[a-z]lurgh" (symbol-name 'foo-blurgh))
["number", 4]
elisp> 
q
js> 

(If you know how to print without a trailing newline in SpiderMonkey
 please let me know.)

There are other interfaces into the parser and evaluator besides the
shortcuts.  new EL.Parser([input]) returns a parser object and likewise
new EL.Evaluator([exprs]) returns an evaluator object.

Mainly toy functions that do extremely simple operations on numbers
and strings can be implemented right now.  Stay tuned, or better yet
hack away and submit a pull request on github[6].

[6] http://github.com/samsonjs/elisp.js


What's here?
============

Not much compared to the real thing but it's a decent start for < 1000
lines.

 * parser/reader. there's no lexing to tokens we go straight to tagged
   data.  (ints, floats, strings, symbols, lists, quoted expressions)

 * symbol table, but needs to be replaced ASAP.
   (functions & variables separate)

 * (broken) lexical scoping

 * expression evaluator

 * simple tagged primitive types
   (string, symbol, lambda, number, cons)

 * special forms for defvar, defun, set, setq, if, and quote

 * eval/apply for atoms, function calls, and a few special forms

 * a few primitive math ops
   (thanks to JS' overloading + works on strings too)

 * 2 horrible print functions
   (JS "pretty" printer & a half-assed Lisp print)