[swift-evolution] Will these two features be included in Swift 3?
Krzysztof Siejkowski
krzysztof at siejkowski.net
Mon Dec 7 06:14:03 CST 2015
Concerning extension constraining, it’s already doable with:
```
protocol DoubleProtocol {}
extension Double : DoubleProtocol {}
extension Array where Element : DoubleProtocol {
func onlyForDoubles() -> String {
return "hello doubles!"
}
}
[1.2].onlyForDoubles() // „hello doubles!”
["a"].onlyForDoubles() // error: type of expression is ambiguous without more context
```
However, I personally like the idea of making a syntactic sugar for that case.
All the best,
Krzysztof
On 7 December 2015 at 13:01:11, Krzysztof Siejkowski (krzysztof at siejkowski.net) wrote:
Concerning generic typealiases, the topic is already being discussed in „Generic `typealias`s” thread: https://lists.swift.org/pipermail/swift-evolution/2015-December/000132.html. The core Swift team approves:
> Yes, this is
definitely something that I (at least) would like to see. Patches
welcome :-)
> Chris (Lattner)
All the best,
Krzysztof
On 7 December 2015 at 12:41:05, Tuur Anton via swift-evolution (swift-evolution at swift.org) wrote:
Can you please add these features in Swift 3?
1. The ability to do this:
extension Array<Double> {
//extend arrays of doubles
}
2. Generic typealiases:
struct Foo<T,V> {
let t: T
let v: V
}
typealias IntFoo<V> = Foo<Int,V> //Error in Swift 2.1
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