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Comment by azakai | Hacker News Reader

> How is coffeescript 'daring' in any way ? It is a thin veneer on top of javascript, syntactic sugar for your coffee.

CoffeeScript does compile into JS, but so does Dart. Both are in that sense just syntactic sugar.

CoffeeScript does make quite big changes to syntax though (often inspired by Ruby, Python, etc.) in many cases more than Dart which seems inspired by Java - and I don't think anyone considers Java 'inspiring' (useful and familiar, sure).

> Dart is a hundred times more daring. It is trying to push optional typing. No mainstream language has such a feature, and not even so much non-mainstream ones.

ActionScript.

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> CoffeeScript does compile into JS, but so does Dart. Both are in that sense just syntactic sugar.

With regards to Dart, that's like saying C++ is just syntactic sugar for assembly. When there's semantic differences between the mapping from one programming domain to another, I would argue that constitutes "compilation". I would agree with the statement for CoffeeScript though.

I don't understand, are you saying Dart doesn't compile to JS?

Dart does compile to JS while CoffeeScript retains a one-to-one mapping between CoffeeScript and JavaScript. Read the "golden rule."[0]

[0]: http://coffeescript.org/

This is a matter of degree.

Dart's types do not affect runtime behavior (at least in the compiled-JS route), so basic types are quite close to JavaScript's, much like CoffeeScript.

There are also no features in Dart that cannot be compiled into JS, like say threading with shared state.

So overall I think it is reasonable to say that both Dart and CoffeeScript are close to JavaScript and built specifically to compile into it.

For the most part it's designed to be easy to compile to JavaScript, but there are bizarre exceptions like support for arbitrary precision integers. (I believe this is ignored by the Dart to JS compiler.)

This is true, and a known bug: http://code.google.com/p/dart/issues/detail?id=1533

> ActionScript

From my understanding, ActionScript is a gradually typed language. Contrast with Dart, which is optionally typed. In Dart, static type annotations do not affect the runtime semantics of the code. In ActionScript, the types do affect the runtime semantics.

> ActionScript.

And Groovy =D

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