js-scheme is a Scheme interpreter written in JavaScript.

The Featured Download is updated every other week or so. New revisions will be added in between each release; see the Source tab for the latest code.

There are two versions of js-scheme. They are identical for the most part - except for that the one tagged CPS supports first-class continuations, while the other only supports continuations as exit procedures. As of version 0.4, no further development is planned for the CPS version.

Libraries

Starting in version 0.4 two extensions are packaged with the main download: a primitive API wrapper for Last.fm Web Services, and an interface to the flot JavaScript graphing library.

The load procedure can be used to load a library. For example, (load 'last.fm) and (load 'flot). After loading, information about a library can be displayed using the help procedure. For example, (help 'last.fm) and (help 'flot). The help message will usually display a list of procedures included with the library.

The convention so far has been for each library to prefix its procedures with its name and a colon mark. For example, last.fm:User.getRecentTracks and flot:plotf.

Library API

Ideally writing a custom library plugin for js-scheme is very easy. A "library" is defined as an extension of the JSCMLib class. The constructor of the library should call $super with the string that it can be loaded with via the load procedure. Library classes should also define name, procedures, and doc fields. name is a string name to display in the help message heading, procedures is a Hash of the Builtin library procedures, and doc is an HTML string to display as the help message body. For example:

var FooBarLib = Class.create(JSCMLib, {
  initialize: function($super) {
    $super('foo-bar');
    this.name = 'FOO BAR LIBRARY';
    this.procedures = new Hash({
      'foo-bar:baz': new Builtin('baz', function(args) { 
        /* do baz */
      }.bind(this), 'This is the baz procedure documentation.', 'arg1 arg2')
    });
    this.doc = '<p>Welcome to the Foo Bar Library!</p>';
  }
}

jscm_registerLib('foo-bar', FooBarLib);

The final step is to call jscm_registerLib with the string loading name again, and the extended library class.

All of the js-scheme classes and procedures are of course available by default to libraries. (More documentation will be provided later in the wiki).