[swift-users] How to add this generic static func as a protocol requirement?

[Slava Pestov]

Try using an associated type for the result of foo():

protocol P {
  associatedtype R

  static func foo<T>(_ v: T) -> R
}

Slava

> On Jul 7, 2017, at 1:50 AM, Jens Persson via swift-users <swift-users at swift.org> wrote:
> 
> protocol P {
>     // …
>     // For example the following will not work:
>     // static func foo<T, R>(_ v: T) -> R
>     // Is there some other way?
>     // …
> }
> struct S2 : P {
>     static func foo<T>(_ v: T) -> (T, T) {
>         return (v, v)
>     }
> }
> struct S3 : P {
>     static func foo<T>(_ v: T) -> (T, T, T) {
>         return (v, v, v)
>     }
> }
> 
> (I'm guessing but am not sure that I've run into (yet) a(nother) situation which would require higher kinded types?)
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