scope of temporary variable

[weepy]

Currently

lunch: eat(food) for food in ['toast', 'cheese', 'wine']

is converted to:

  var __a, __b, __c, __d, food, lunch;
  lunch = (function() {
    __a = ['toast', 'cheese', 'wine'];
    __c = [];
    for (__b in __a) {
      if (__a.hasOwnProperty(__b)) {
        food = __a[__b];
        __d = eat(food);
        __c.push(__d);
      }
    }
    return __c;
  })();

shouldn't it be:

  var food, lunch;
  lunch = (function() {
    var __a, __b, __c, __d;
    __a = ['toast', 'cheese', 'wine'];
    __c = [];
    for (__b in __a) {
      if (__a.hasOwnProperty(__b)) {
        food = __a[__b];
        __d = eat(food);
        __c.push(__d);
      }
    }
    return __c;
  })();

[jashkenas]

Hmm, that's a fair question -- we're actually taking special care in this case to ensure that variables within the comprehension are declared first outside of it. If you write a comprehension, but don't use it as part of an expression, then no closure wrapper is generated ... a comprehension isn't a function, in CoffeeScript, and doesn't imply function scope. Whether it needs to be wrapped in one or not is determined by where it occurs. It would be awfully strange if sometimes you could set variables from within a comprehension, and sometimes you couldn't -- so, to alleviate that, the auto-closures share a scope with their parent node. Sound alright?

[jashkenas]

No objections then ... closing the issue.