[Belt] Make comparable label-less

[chenglou]

It's a single arg, so reduces the burden of using that pattern a little.

I'll update the docs after this

[chenglou]

cc @cristianoc

[bobzhang]

I thought about this. The thing is that when creating hashtbl, you need to pass ~hash ~eq, to make it more consistent, I chose to keep it.

[chenglou]

It's not inconsistent not to have a label, especially when the call's name is comparable though. I'm trying to address the feedback and make this piece of boilerplate a bit easier to swallow.

module IntCmp = (
  val Belt.Id.comparable((x: int, y) => Pervasives.compare(x, y))
);

let s = make(~id=(module IntCmp));

[rickyvetter]

Yeah I think ~cmp is redundant with comparable and is hard to understand when seen/used by itself (component, compute both could be shortened to cmp). Since neither of those two outcomes are desirable I'd prefer to remove as well.

[chenglou]

Discussed offline