Re:Closure Mode for CoffeeScript
by jashkenas on Friday August 05, 2011 @05:25PM
(#2851844)
Fair enough ... it's definitely worth considering seriously. I'd probably wait until it's "finished" according to Michael, and then look at if it's possible to add enough hooks to the compiler for it to be implemented as a plugin. Ideally you'd be able to emit different annotations depending on your use case, for example: lots of other folks have requested automatic JSDoc annotations.
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What's the chance of also getting optional Type Annotations into CoffeScript core as well?
As this would greatly help the closure compiler do optimisations, and since it is opt-in to add the typed parameter and would only produce a javascript comment above said variable.
For example....
foo <: String = "hey"
/* @type {String} */ var foo = "hey"
I don't think this is deviating from CoffeeScript's aim to keep things pure? Is it?
It is deviating pretty far from compiling to readable, standard JS, but again ... as a fork or a plugin, I'm all for it. The reason why the entire CoffeeScript source is annotated is to make variants like this easier to accomplish.
That said, statically marking your variables with "types" (where types are incredibly weak and limited in JavaScript) isn't going to be of much use to you, performance-wise. Modern engines like V8 already unbox local variables where possible, and do "hidden class" analysis to give a "type" even to regular unstructured JS objects.
What I'm after for typed annotations is integration with the closure compiler to give me static checking, so in large codebases I get that type safety, even in javascript.
Thanks anyways though
A standard way of doing type annotations would also make it possible to generate AS3 code with CoffeeScript.