> On Jul 1, 2016, at 2:08 AM, Cao Jiannan via swift-evolution
> <[email protected]> wrote:
>
>
>
> Hi all,
>
> I'm now officially proposal the union type feature for Swift. Please see:
>
>
> https://github.com/frogcjn/swift-evolution/blob/master/proposals/xxxx-union-type.md
> Introduction
>
> Add union type grammar, represents the type which is one of other types.
>
> var stringOrURL: String | URL = "https://www.apple.com";
>
>
> I would be thankful if someone support this idea and give some advice. Thanks!
We touch on this in the "commonly proposed" list:
https://github.com/apple/swift-evolution/blob/master/commonly_proposed.md
Disjunctions (logical ORs) in type constraints
<https://lists.swift.org/pipermail/swift-evolution-announce/2016-June/000182.html>:
These include anonymous union-like types (e.g. (Int | String) for a type that
can be inhabited by either an integer or a string). "[This type of constraint
is] something that the type system cannot and should not support."
-Joe
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