Because it is badly designed? Or because it is too different from js?
Since you mentioned the => operator in particular, I'll defend it briefly-- it's a feature JavaScript sorely needs, and in the situations where it's useful it's a godsend, turning a pile of ugly JS into a single operator. The thing it describes is a little complex semantically, but in practice it's very straightforward, and in the cleaner environment of CoffeeScript it stands out well. It does seem like a small difference, but do you mix up == and -= much? Same deal. Visually speaking it actually makes a lot of sense: -> indicates a vanilla, unbound function, while => indicates a bound function whose context equals the one it's defined in.
I know I'm a bit of a fanboy, but if you do a lot of JavaScript I'd encourage you to at least give CoffeeScript a second chance over a weekend sometime; it's the same, normal JS semantics you know and love, but you get to use all the futuristic shortcuts and clean syntax of a modern scripting language, and it outputs nice, readable, compliant JavaScript. (Say goodbye to JSLint!) That's well worth the minimal learning curve, in my opinion of course.
Oh I understand the need for it, my issue is not with the fat arrow in and of itself, but in the fat arrow and the thin arrow.
> It does seem like a small difference, but do you mix up == and -= much? Same deal.
Well...
1. I rarely if ever use either, and
2. they're generally used in different contexts, I would never use `-=` as part of a wider expression (unless I wanted to fuck with the reader of the code, who is usually me) whereas `==` is not very useful outside of a conditional expression (or at least as a parameter to something else, like a function).
The thin and fat arrows, by comparison, are used in the exact same contexts. This makes them much more error prone.
> That's well worth the minimal learning curve, in my opinion of course.
I don't mind the learning curve, I mind that I don't really like the way the syntax fits together (or does not). Though, to be fair, I also don't like the extra tooling or having to debug different code than was written.
You can say that, but in practice it doesn't really happen. They look somewhat different, they do somewhat different things. It's programming, ya know?
Not that I'm trying to make you like it or anything-- of course you have the right to your own aesthetic sensibility.