improvements

Size/Speed

$ git log -1 --oneline
9e4fa02 CoffeeScript 1.1.1

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

$ cake loc
2418

$ cake bench
Lex     1597 ms (21836 tokens)
Rewrite  220 ms (24350 tokens)
Parse    293 ms
Compile  193 ms (132096 chars)
total   2303 ms

$ cd ../coco

$ git log -1 --oneline
7e5344b 0.5.3

$ ls -sk extras/co*.js
132 extras/coco.js

$ coke loc
2322

$ coke bench
Lex      421 ms (23770 tokens)
Rewrite  170 ms (27709 tokens)
Parse    187 ms (24085 nodes)
Compile  193 ms (140362 chars)
TOTAL    971 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 name

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

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

line number

$ coffee -bpe 'x = (return)'
SyntaxError: cannot use a pure statement in an expression.
...

$ coco -bpe 'x = (return)'
SyntaxError: inconvertible statement on line 1
...

space/tab contamination

$ cat space_tab.coffee
if 0
        console.log 1
        console.log 2

$ coffee space_tab.coffee
2

$ coco space_tab.coffee
Failed at: space_tab.coffee

SyntaxError: contaminated indent %09 on line 2

misdentation

$ cat misdent.coffee
if 0
    console.log 1
  console.log 2

$ coffee misdent.coffee
2

$ coco misdent.coffee
Failed at: misdent.coffee

SyntaxError: unmatched dedent (2 for 4) on line 3

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