[swift-evolution] Partial list of open Swift 3 design topics

[Douglas Gregor]

> On Jun 27, 2016, at 10:40 PM, Charlie Monroe <charlie at charliemonroe.net> wrote:
> 
> Oh, I see. The issue is then the following:
> 
> let x = f
> x(1, 2) // Error: Missing argument labels 'a:b:' in call
> 
> let y: (Int, Int) -> () = f
> f(1, 2) // OK
> 
> Which requires you to write x(a: 1, b: 2). I must admit, however, that I always liked this behavior…

Right, that’s the issue. The idea behind this is that it’s a simplification to the type system to eliminate argument labels from types, so we can eliminate some extra subtyping relationships (e.g., between function types with labels and ones without labels). Essentially, argument labels become part of the names of declarations (only!), which is consistent with our view that the names of functions/methods/initializers include all of the argument names.

	- Doug

> 
>> On Jun 28, 2016, at 7:06 AM, Austin Zheng <austinzheng at gmail.com> wrote:
>> 
>> I think the point is to get rid of the argument labels. 'x' should be typed simply (Int, Int) -> ().
>> 
>> That being said, right now the argument labels in the type don't seem to actually affect anything, so like Chris I'm not sure what the counter-proposal is.
>> 
>> (cc. Doug)
>> 
>> Best,
>> Austin
>> 
>>> On Jun 27, 2016, at 10:04 PM, Charlie Monroe <charlie at charliemonroe.net> wrote:
>>> 
>>>> This came from a short list of topics Doug provided me, but the basic issue is that:
>>>> 
>>>> func f(a : Int, b : Int) {
>>>> let x = f   // x has type (a: Int, b: Int) -> ()
>>>> }
>>>> 
>>>> I’m not exactly sure what the counterproposal is.
>>> 
>>> My guess is to require let x = f(a:,b:) (specifying arguments)?
>>> 
>>>> 
>>>> -Chris
>>>> 
>>>> 
>>>> 
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>>> 
>> 
>