Sure. One of the first gadgets I wrote was a way of destructuring an array into a familiar cons-list kind of enum (https://github.com/typelift/Basis/blob/master/Basis/Array.swift#L9) which you use something like this with other non-trivial enums (https://github.com/typelift/Valence/blob/cf4353c64de93b98c460529b06b8175c9ecfb79b/Tests/SystemF.swift#L161).
It's not strictly a problem for me to lose this feature, but it is gonna be a bit weird if we lose recursive match but also allow it for just plain old tuple patterns. ~Robert Widmann 2017/01/22 3:02、Daniel Duan <dan...@duan.org> のメッセージ: > FWIW, in all public Github repos with 5k+ stars whose language gets > recognized as “Swift”, 576 enum cases has associated values and among them 55 > has 2 values or more. After some very casual grepping I didn’t find a lot of > usage of this particular pattern. > > Care to share some examples, Robert? > > - Daniel Duan > >> On Jan 21, 2017, at 11:00 PM, Robert Widmann <devteam.cod...@gmail.com> >> wrote: >> >> I find myself doing this a lot, but maybe my problems are just more >> Algebra-shaped than most. That said, I appreciate this cleanup and lean +1 >> (because you mentioned a way to partly keep this behavior). >> >> ~Robert Widmann >> >> 2017/01/19 18:14、Joe Groff via swift-evolution <swift-evolution@swift.org> >> のメッセージ: >> >>> >>>> On Jan 19, 2017, at 2:58 PM, Daniel Duan <dan...@duan.org> wrote: >>>> >>>> >>>>>>> On Jan 19, 2017, at 2:29 PM, Joe Groff <jgr...@apple.com> wrote: >>>>>> >>>>>> >>>>>> On Jan 19, 2017, at 1:47 PM, Douglas Gregor via swift-evolution >>>>>> <swift-evolution@swift.org> wrote: >>>>>> >>>>>> This looks totally reasonable to me. A couple of comments: >>>>>> >>>>>> 1) Because this proposal is breaking the link between the associated >>>>>> value of an enum case and tuple types, I think it should spell out the >>>>>> rules that switch statements will use when matching an enum value >>>>>> against a a case with an associated value. Some kind of rules fell out >>>>>> of them being treated as tuple types, but they might not be what we want. >>>>> >>>>> I was about to bring up the same. Right now, an enum pattern works like >>>>> .<identifier> <tuple-pattern>, where the <tuple-pattern> then recursively >>>>> matches the payload tuple. In this model, it seems like we'd want to >>>>> treat it more like .<identifier>(<pattern>, <pattern>, ...). Similar to >>>>> how we lost "tuple splatting" to forward a bunch of arguments, we'd have >>>>> to decide whether we lose the ability to match all parts of the payload >>>>> into a tuple. >>>> >>>> I’m leaning towards “no” for simplicity of the language (and >>>> implementation). That means this would be source-breaking 😞. Will update >>>> the proposal and see how the rest of the feedback goes. >>> >>> It'd be a good idea to try to find examples of people doing this out in the >>> wild too, to see how widespread it is as well as how onerous the >>> workarounds for losing the feature would be. >>> >>> -Joe >>> >>> _______________________________________________ >>> swift-evolution mailing list >>> swift-evolution@swift.org >>> https://lists.swift.org/mailman/listinfo/swift-evolution >
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