> On Dec 21, 2015, at 10:33 PM, Zef Houssney <[email protected]> wrote:
>
> I agree with Stephen Celis that the best names for this (yet) are definitely
> `cases` and optionally `rawValues` if the cases are RawRepresentable.
>
> Regarding handling cases with associated values where some of those values
> are other enums, it seems odd to me to try to return every variation of each
> case. I can’t picture how that would work sanely when there are multiple
> associated values, such as a case like `MyCase(String, SomeEnum)`. Therefore
> I prefer the idea of having the array contain the constructor for cases with
> associated values. The main problem I see here is that the type system (as
> far as I know) can’t fully represent that type of thing, but I think it’s
> still potentially valuable. Related to this I’m putting together a separate
> proposal that explores a bit more on why I believe the enum constructor to be
> valuable, though that’s in a bit of a different context.
Generating a list of values for MyCase(String, SomeEnum) wouldn't make sense
because there are an infinite number of Strings, so Strings don't make sense as
a value-enumerable type. However, you could have a mostly-flat enum that uses
subenums for organization:
enum Food {
enum Fruit {
case Apple, Banana, BellPepper
}
case fruit(Fruit)
enum Meat {
case Beef, Pork, Venison
}
case meat(Meat)
}
In many C family code bases it's common to group related enums by order, even
if there's otherwise no intrinsic order among the elements. Preserving the
structure of the cases in the type system makes them easier to understand and
work with in pattern-matching, since you can handle all fruits by matching
`.fruit(_)` instead of having to maintain `food >= FirstFruit && foo <=
LastFruit` ranges. For these kinds of enums, recursively generating the
associated values is still useful.
-Joe
> I shared these thoughts in a bit more detail here a couple weeks ago, with
> some followup in the next two messages:
>
> https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20151207/001864.html
>
> Zef
>
>
>
>> On Dec 21, 2015, at 3:58 PM, Erica Sadun via swift-evolution
>> <[email protected]> wrote:
>>
>> That would be okay too. Thank you, Santa Joe.
>>
>> -- E, who hopes she was on the nice list.
>>
>>> On Dec 21, 2015, at 3:56 PM, Joe Groff <[email protected]> wrote:
>>>
>>>
>>>> On Dec 21, 2015, at 12:24 PM, Erica Sadun <[email protected]> wrote:
>>>>
>>>> I could be satisfied by such an approach. I could even be more satisfied
>>>> if
>>>>
>>>>> enum Foo: ValueEnumerable { case A, B, C }
>>>>
>>>>
>>>> were also essentially an alias for
>>>>
>>>>> enum Foo: Int, ValueEnumerable { case A=0, B, C }
>>>>
>>>> :)
>>>
>>> If the value collection were sufficiently capable, you wouldn't necessarily
>>> need an implicit Int raw value; you could do `allValues.indexOf(.A)` to get
>>> the index for a case.
>>>
>>> -Joe
>>>
>>
>> _______________________________________________
>> swift-evolution mailing list
>> [email protected]
>> https://lists.swift.org/mailman/listinfo/swift-evolution
>
_______________________________________________
swift-evolution mailing list
[email protected]
https://lists.swift.org/mailman/listinfo/swift-evolution
