[stoodder]

Why not allow CoffeeScript to use the 'var' keyword, explicitly telling CS that this variable should be scoped locally even though it may be shadowing another variable? This seems consistent with their approach of allowing (although optional) native javascript syntax such as {}, and []. This still allows CS to stick to it's paradigm of forbidding shadowing unless we explicitly state that we know what we're doing.

[jashkenas]

Because we're aiming for a conceptual simplification.

Pretend like you're a beginner, learning this stuff for the first time. If everywhere you see a variable "A", within a certain lexical scope, it means the same thing ... that's much simpler to understand than if "A" means three different things at three different places, because you happened to shadow it twice.

[stoodder]

Yea, I completely get what you're saying and for the most part agree. To be frank, I think the author of the article made an error in deconstructing on the 'Math' object (at least at a global scope). 'Math' provides a namespace for all of its methods and a similar approach should be taken to other libraries/pieces of code. I also agree that keeping things simple and straight forward makes sense, but you're doing it by forcing one to abide by those standards although someone might have completely legitimate reasons for explicitly scoping their variables.

Either way, I think it is what it is and the benefits of CS very much outweigh the cons. Thanks for the feedback