[swift-evolution] [Proposal][Discussion] Deprecate Tuple Shuffles

[Adrian Zubarev]

I still have to disagree on that. Tuple patterns are not consistent in Swift.

Here is a small proof of my claim:

enum Foo {
     
    case a(b: Int)
}

switch Foo.a(b: 10) {
     
case .a(b: let x):
    print(x)
}

let tuple = (x: 2, y:  20)

switch tuple {
     
case (x: let a, y: let b):
    print(a); print(b)
}

(x: let a, y: let b): (x: Int, y: Int) = tuple // Error!!!
Tuple destructuring only works using the shorthand pattern, which _can_ lead to all those puzzles from the discussion.

The shorthand form ‘Is good and beautiful’ (German proverb), but it can do more harm than it should. Personally I would entirely ban the shorthand version unless we’ve got a superior version of it without all these issues.

By the way not only tuples are affected by the mentioned puzzle:

enum Foo {
     
    case sum(x: Int, y: Int)
}

switch Foo.sum(x: 3, y: 1) {
     
case let .sum(x: Int, y: Double):
    print(Int + Double) // prints 4
}


-- 
Adrian Zubarev
Sent with Airmail

Am 8. Mai 2017 um 09:28:52, Xiaodi Wu via swift-evolution (swift-evolution at swift.org) schrieb:

But, in any case, with respect to consistency with the rest of the language, tuple patterns with labels are *supremely* consistent.
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