[Pitch] Enum Composition

[Chuquimia_Max (Max Chuquimia)]

@sveinhal

let number: (Int | Float) = ...

// this would create an enum like so
// enum Either<Int, Float> {
//    case 0(Int)
//    case 1(Float)
// }

This is pretty nice actually - and I suppose if all of the types had a common conformance then the synthesized Either would have it too (so that we can still pass around Errors etc as in the original example). And, of course, if they were both enums then this should still work:

@hishnash

typealias AB = A | B

let state: AB = ...

switch state {
    case .error: 
        ....
    case A.progress(let value):
       ...
    case B.progress(let value):
      ...
...
}