I don’t get the part how `all<>` should allow `any<>`. Could you explain that a
little bit in detail (I’m not familiar with Ceylon)?
>From my point of view `any<>` is something different that I pitched here.
>`any<>` could be proposed in its own thread, because it is way different than
>`type<>`. Or can we refine the rules of `type<>` to get to `any<>`?
Here is a little example where `any<>` gets strange:
func foo(value: any<String, Int>) -> any<String, Int> {
// how would one use value here?
// what about its properties
// what will foo return and how to use the result
}
One benefit of `any<>` is the replacement of overloading, at least for the type
part of the function.
I’d like to propose `type<>` as the base extension to the language in that
direction, before we’ll move forward with more complex scenarios (just like
Chris did with generic typealias).
This function is clear that it only will work if you provide a subclass of an
UIView which conforms to SomeProtocol (nice addition for library design).
func foo(value: type<UIView, SomeProtocol>) -> type<UIView, SomeProtocol> {
// use it as a UIView and SomeProtocol at the same type
return value // return type works great
}
We can split the value just fine:
let mergedValue = foo(SomeViewThatWorks)
let view: UIView = mergedValue
let protocolValue: SomeProtocol = mergedValue
And merge it back together:
guard let newMergedValue = view as? type<UIView, SomeProtocol> else { /* do
something */ }
`all<>` could be seen as an alternative name for `type<>`, but to me its not
clear what `all<>` can do, whereas `type<>` is almost like `protocol<>`.
--
Adrian Zubarev
Sent with Airmail
Am 12. Mai 2016 bei 21:40:24, Thorsten Seitz (tseit...@icloud.com) schrieb:
Ceylon uses „&" for intersection types, i.e.
SomeRealClass & SomeProtocol
and the bar („|“) for union types, i.e.
String | Int
That has proven to be very lightweight and readable in Ceylon where it is
heavily used to good effect.
I agree with you that
type<SomeRealClass, SomeProtocol>
is much nicer than protocol<> for intersection types but to keep the door open
for union types, I would prefer
all<SomeRealClass, SomeProtocol>
This would allow
any<String, Int>
to be used for union types.
-Thorsten
Am 12.05.2016 um 16:09 schrieb Adrian Zubarev via swift-evolution
<swift-evolution@swift.org>:
protocol<SomeRealClass, SomeProtocol>
protocol<SomeRealStruct, SomeProtocol>
This feels really odd to me.
`type<SomeRealClass, SomeProtocol>` is more clear I’d say.
I think this would be a good addition to the type system and allow us to build
more complex and type save code.
But still I’d love to discuss if there might be any disadvantages to this
feature.
--
Adrian Zubarev
Sent with Airmail
Am 12. Mai 2016 bei 15:11:00, Vladimir.S (sva...@gmail.com) schrieb:
protocol<>
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