[swift-evolution] [swift-evolution-announce] [Review] SE-0089: Replace protocol<P1, P2> syntax with Any<P1, P2>

[Thorsten Seitz]

We could just write

let x: P & Q
instead of
let x: Any<P, Q>

let x: Collection where .Element: P
instead of
let x: Any<Collection where .Element: P>

let x: P & Q where P.T == Q.T
instead of
let x: Any<P, Q where P.T == Q.T>

let x: P & Q & R
instead of
let x: Any<P, Q, R>

let x: Collection
instead of
let x: Any<Collection>


This would avoid the confusion of Any<T1, T2> being something completely different than a generic type (i.e. order of T1, T2 does not matter whereas for generic types it is essential).


-Thorsten



> Am 26.05.2016 um 20:11 schrieb Adrian Zubarev via swift-evolution <swift-evolution at swift.org>:
> 
> Something like type<…> was considered at the very start of the whole discussion (in this thread <https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160502/016523.html>), but it does not solve the meaning of an existential type and also might lead to even more confusion. 
> 
> From my perspective I wouldn’t use parentheses here because it looks more like an init without any label Type.init(…) or Type(…). I could live with Any[…] but this doesn’t look shiny and Swifty to me. Thats only my personal view. ;)
> 
> 
> 
> 
> -- 
> Adrian Zubarev
> Sent with Airmail
> 
> Am 26. Mai 2016 bei 19:48:04, Vladimir.S via swift-evolution (swift-evolution at swift.org <mailto:swift-evolution at swift.org>) schrieb:
> 
>> Don't think {} is better here, as they also have "established meaning in 
>> Swift today".
>> 
>> How about just Type(P1 & P2 | P3) - as IMO we can think of such 
>> construction as "creation" of new type and `P1 & P2 | P3` could be treated 
>> as parameters to initializer.
>> 
>> func f(t: Type(P1 & P2 | P3)) {..}
>> 
>> 
>> On 26.05.2016 20:32, L. Mihalkovic via swift-evolution wrote:
>> > How about something like Type{P1 & P2 | P3} the point being that "<...>" has an established meaning in Swift today which is not what is expressed in the "<P1,P2,P3>" contained inside Any<P1, P2,P3>.
>> >
>> >> On May 26, 2016, at 7:11 PM, Dave Abrahams via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> >>
>> >>
>> >>> on Thu May 26 2016, Adrian Zubarev <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> >>>
>> >>> There is great feedback going on here. I'd like to consider a few things here:
>> >>>
>> >>> * What if we name the whole thing `Existential<>` to sort out all
>> >>> confusion?
>> >>
>> >> Some of us believe that “existential” is way too theoretical a word to
>> >> force into the official lexicon of Swift. I think “Any<...>” is much
>> >> more conceptually accessible.
>> >>
>> >>>
>> >>> This would allow `typealias Any = Existential<>`. * Should
>> >>> `protocol A: Any<class>` replace `protocol A: class`? Or at least
>> >>> deprecate it. * Do we need `typealias AnyClass = Any<class>` or do we
>> >>> want to use any class requirement existential directly? If second, we
>> >>> will need to allow direct existential usage on protocols (right now we
>> >>> only can use typealiases as a worksround).
>> >>
>> >> --
>> >> Dave
>> >>
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