`if let` shorthand

[cal (Cal Stephens)]

@Ben_Cohen discussed this somewhat recently in a reply to Let's fix if let syntax:

@Ben_Cohen

Speaking personally, not on behalf of the core team:

I agree this is something worth addressing. if let x = x { } is so incredibly common that it clearly deserves some form of privileged syntax.

...

Regarding the commonly rejected list: people should take note of it, and the core team has added to it recently. But it needn't be treated as inviolable – we have also removed entries from it when sufficiently well-motivated proposals have come along (though note, the proposal that prompted that removal was rejected following review).

So I get the impression that there is some openness to considering this sort of proposal.

I agree with @bzamayo's point here:

@bzamayo

Typing out that the same thing equals the same thing is no more syntactically meaningful than the proposed ‘if let x’ and the extra characters just seem like unnecessary noise.

imho this proposed syntax doesn't "favor terseness over clarity" because it is equally as clear as the existing syntax (or at least isn't any more "magical" than the existing syntax). And if it's equally / sufficiently clear, then reducing duplication seems like a clear readability win.