> On 16 Feb 2017, at 23:44, Matthew Johnson via swift-evolution
> <[email protected]> wrote:
>
> I have been thinking a lot about enums and value subtyping lately and decided
> to write down the ideas I’ve been thinking about. The result is a
> manifesto-style document that explores a broad landscape of features that
> could eventually lead to proposals (at the right time, of course).
>
> I’m presenting this document to the list now mostly because I am not sure
> which of these features (if any) might be relevant to ABI stability,
> particularly with respect to standard library APIs. I do not wish to
> distract the list from the focus on Swift 4, phase 1. Let’s try not to get
> distracted by exciting ideas that won’t be in scope until at least phase 2.
> Feel free to send feedback off list if you’re interested in discussing ideas
> that may not be relevant to Swift evolution at this time.
>
> Because this document covers a pretty broad range of topics it might be a
> good idea to start a new thread before jumping in to discussion about a
> specific aspect of it. Please consider doing that if it is relevant before
> responding directly to this thread.
>
> As this is a relatively large document I am only providing a link:
> https://gist.github.com/anandabits/5b7f8e3836387e893e3a1197a4bf144d
>
> To whet your appetite, the topics covered include:
>
> * Definition of value subtyping
> * Transitivity of value subtypes
> * Generic supertype constraints
> * Axiomatic value subtype relationships
> * Enums: Value Subtype Relationships by definition
> * Nominal case types
> * Nominal unions
> * Generic enums and Optional
> * Cases with unbound generic arguments
> * Structural Unions
> * Enum subtypes
> * Inline enum subtypes
> * Inline generic enum subtypes
> * Conditional cases (and GADTs)
> * Inline case types
> * Nominal cases with inline types
> * Case type implementation sharing
> * Shared stored properties
> * Subenum stored properties
> * Shared methods and computed properties
> * User-defined case patterns
> _______________________________________________
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> [email protected]
> https://lists.swift.org/mailman/listinfo/swift-evolution
enum IntOrString: Int | String {
case Int
case String
}
func takesAnonymousUnion(intOrString: Int | String) {}
Haven’t been through it all, just pointing out that “Structural unions” and
anonymous unions have been suggested and rejected before.
- Karl_______________________________________________
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