[swift-evolution] Swift Closure still inconsistent -- tuple names need to be in curly brackets, single parameter needs to be in parentheses

[Derrick Ho]

The core team designed swift blocks to range from concise to verbose. Which
one you use depends on your needs.

If you want to write parenthesis then by all means write parenthesis; no
one is stopping you.

I would rather keep the block syntax as it is so that everyone can choose
the style that matches their needs.

On Mon, Dec 19, 2016 at 1:52 PM Xiaodi Wu via swift-evolution <
swift-evolution at swift.org> wrote:

> This issue about `numbers in` was raised during review of SE-0066; if I
> recall, the core team considered and rejected disallowing that syntax in
> closures. Since we're minimizing source-breaking changes, the issue is
> settled in my view, having been proposed, commented upon, reviewed, and
> rejected.
> On Mon, Dec 19, 2016 at 15:39 Anton Zhilin via swift-evolution <
> swift-evolution at swift.org> wrote:
>
> 2016-12-17 2:55 GMT+03:00 Vip Malixi via swift-evolution <
> swift-evolution at swift.org>:
>
>
> var oneParameterAndMultipleReturn: ([Int]) -> (even:[Int], odd:[Int]) = {
> numbers -> ([Int], [Int]) in
>     var evenNumberArray = [Int]()
>     var oddNumberArray = [Int]()
>
>     for number in numbers {
>         number % 2 == 0 ? evenNumberArray.append(number) :
> oddNumberArray.append(number)
>     }
>
>     return (evenNumberArray, oddNumberArray)
> }
>
>
>
> The above code is valid, because:
>
>
>
>
>
>    1. Multi-return is just a type of tuple with labeled components.
>
>    2. Labeled tuples and normal tuples are implicitly convertible.
>
>
>
>
> The only way we could make such code invalid is by removing labeled tuples
> altogether. -1 on that.
> This problem mostly refers to code style, and the above variant can be
> more self-documenting in some cases.
>
>
> Also, again for consistency and clarity, parameters in Closures should
> always be surrounded by parentheses, even single parameters:
>
> var oneParameterAndMultipleReturn: ([Int]) -> ([Int], [Int]) = { (numbers)
> -> (even:[Int], odd:[Int]) in
>     var evenNumberArray = [Int]()
>     var oddNumberArray = [Int]()
>
>     for number in numbers {
>         number % 2 == 0 ? evenNumberArray.append(number) :
> oddNumberArray.append(number)
>     }
>
>     return (evenNumberArray, oddNumberArray)
> }
>
>
>
> This should be considered a bug. numbers in or (numbers) in or (numbers)
> -> (...) in, but not numbers -> (...) in, because the latter forms should
> be correct types.
> Whether or not just numbers in should be allowed, is another talk.
>
>
> ​
>
>
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