sweet.js

Hygienic Macros for JavaScript!

Documentation at sweetjs.org.

Overview and motivation in this talk.

Early stage at the moment. Lots of bugs so be warned!

Use

Clone sweet.js and then install its dependencies:

$ npm install underscore optimist escodegen

To try it out make a file test_macros.sjs:

// functions can now be spelled def!
macro def {
  case $name:ident $params $body => {
    function $name $params $body
  }
}
def add (a, b) {
  return a + b;
}

console.log( add(3, 7) );

And compile it with sjs:

$ bin/sjs -o output.js test_macros.sjs
$ node output.js
10

Alternately you can require an sjs file from node. For example, in main.js add:

var sjs = require('sweet.js'),
    example = require('./example');

example.one;

Where ./example.sjs contains:

macro A {
    case ($a + $b) => {
        $a
    }
}

exports.one = A(1 + 2);

And just run main.js in node.

Ruby gem

To compile sweet.js source files from within Ruby, use the SweetJS gem:

gem install sweetjs

or in your Gemfile:

gem "sweetjs"

then call the SweetJS.compile (or SweetJS#compile) method to compile a sweet.js source file to plain JavaScript:

require "sweetjs"

SweetJS.compile(File.read("macros.js.sjs"))
# => Resulting JS source

# Alternatively:
sweet  = SweetJS.new
source = File.open("macros.js", "r:UTF-8").read
js     = sweet.compile(source)

Hacking

Install the dev dependencies:

$ npm install --dev

And run the tests

$ npm test