Monday, March 3, 2008

Generics in Javascript

Apparently, there are talks about adding generics to Javascript.

I'm not sure why people would want generics in a dynamically-typed language.

Personally, I like:

var EmpList = []
var EmpList:List.<Employee> = new List.<Employee>();

The one thing I really dislike about static typed languages is this naive assumption that a language should restrict the "damage" a programmer can do. I think that's just plain bad design, because people end up relying on the software when it's really the programmer's job to unit-test their code in the first place.

Making generics invariant is just silly. In the EmpList example, writing

is going to throw errors regardless of whether you have type constraints or not. This whole thing about object sniffing has been discussed enough times already and this sounds like a pompous version of the same thing. When you have no control over the environment where your code will run (e.g. a browser), you can't just go and do
var a = new List.<Array>([]);

At least they're suggesting an unambiguous token (".<"), instead of copying Java literally, so implementation should be a little less hellish, and thus, a little faster to parse through.

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