[swift-evolution] guard let x = x

[Pyry Jahkola]

Going back to the originating message of this thread. This idea (or a variant thereof) has been mentioned in the list of Commonly Rejected Proposals (2nd last bullet under Control Flow, Closures, Optional Binding, and Error Handling <https://github.com/apple/swift-evolution/blob/master/commonly_proposed.md#control-flow-closures-optional-binding-and-error-handling>):

> Syntactic sugar for if let self-assignment <https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160829/026796.html>: An alternative syntax (such as if let foo? { ... } or if let foo=? { ... }) to serve as a shorthand for if let foo = foo { ... } is often proposed and rejected because it is favoring terseness over clarity by introducing new magic syntactic sugar.

So any discussion on this topic would have to target these concerns first.

> On 26 Oct 2016, David Goodine wrote:
> 
> I was typing the above (for the hundredth time) the other day and I was wondering whether it might be worth considering offering a shorter syntax:
> 
> guard let x, y, z else {…}


That said, while I don't mind having to repeat the variable name myself, I think David Goodine's syntax would have to repeat the `let` to align with SE-0099 <https://github.com/apple/swift-evolution/blob/master/proposals/0099-conditionclauses.md>, like so:

    guard let x, let y, let z else { ... }

Personally, I wouldn't mind if this syntax existed. I think it explains itself rather well. And today, unlike when it was first discussed a long time before SE-0099, it's no longer confusable with Boolean conditions.

But it's certainly out of scope for Swift 4 phase 1.

— Pyry

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