improvements

Size/Speed

$ git log -1 --format=oneline
09712603c4638933ec86efffc919c270e41256ad coffee-script 1.1.0

$ ls -sk extras/*.js
160 extras/coffee-script.js

$ cake loc
2411

$ cake bench
Lex     2353 ms (21690 tokens)
Rewrite  227 ms (24177 tokens)
Parse    274 ms
Compile  225 ms (131059 chars)
total   3079 ms

$ cd ../coco

$ git log -1 --format=oneline
4d51b68e94bc71f10851015566000a8c08961742 0.5.0

$ ls -sk extras/*.js
128 extras/coco.js*

$ coke loc
2276

$ coke bench
Lex     2123 ms (23037 tokens)
Rewrite  179 ms (26858 tokens)
Parse    225 ms (23342 nodes)
Compile  153 ms (136071 chars)
TOTAL   2680 ms

Temporary Variables

Coco uses them more wisely than Coffee, making generated code cleaner and/or faster.

$ coffee -bpe '[i for i in a]'
var i;
[
  (function() {
    var _i, _len, _results;
    _results = [];
    for (_i = 0, _len = a.length; _i < _len; _i++) {
      i = a[_i];
      _results.push(i);
    }
    return _results;
  })()
];

$ coco -bpe '[i for i of a]'
var i;
[
  (function(){
    var _i, _ref, _len, _results = [];
    for (_i = 0, _len = (_ref = a).length; _i < _len; ++_i) {
      i = _ref[_i];
      _results.push(i);
    }
    return _results;
  }())
];


$ coffee -bpe 'a < b() < c; d > e() > f'
var _ref, _ref2;
(a < (_ref = b()) && _ref < c);
(d > (_ref2 = e()) && _ref2 > f);

$ coco -bpe 'a < b() < c; d > e() > f'
var _ref;
a < (_ref = b()) && _ref < c;
d > (_ref = e()) && _ref > f;


$ coffee -bpe '=> this'
var __bind = function(fn, me){ return function(){ return fn.apply(me, arguments)
; }; };
__bind(function() {
  return this;
}, this);

$ coco -bpe '~> this'
var _this = this;
(function(){
  return _this;
});


$ coffee -bpe 'r = for k of o then arguments'
var k, r;
r = (function() {
  var _results;
  _results = [];
  for (k in o) {
    _results.push(arguments);
  }
  return _results;
}).apply(this, arguments);

$ coco -bpe 'r = for k in o then arguments'
var k, r;
r = (function(_args){
  var _results = [];
  for (k in o) {
    _results.push(_args);
  }
  return _results;
}(arguments));

Compile Errors

variable safety

$ coffee -bpe 'Math += 1'
Math += 1;

$ coco -bpe 'Math += 1'
SyntaxError: assignment to undeclared variable "Math" on line 1

duplicate keys

$ coffee -bpe 'a:1, a:2'
({
  a: 1,
  a: 2
});

$ coco -bpe 'a:1, a:2'
SyntaxError: duplicate property name "a" on line 1

invalid call

$ coffee -bpe '[]()'
[]();

$ coco -bpe '[]()'
SyntaxError: invalid callee on line 1

invalid regex

$ coffee -bpe '/+/'
/+/;

$ coco -bpe '/+/'
SyntaxError: Invalid regular expression: /+/: Nothing to repeat on line 1