[swift-evolution] protocol-oriented integers (take 2)

Dave Abrahams dabrahams at apple.com
Mon Jan 30 13:25:05 CST 2017

on Mon Jan 30 2017, Brent Royal-Gordon <swift-evolution at swift.org> wrote:

>> On Jan 29, 2017, at 10:07 PM, Dave Abrahams <dabrahams at apple.com> wrote:
>>>>> It might make a great deal of sense to support bitwise operations on
>>>>> this type, 
>>>> I think that's a model of SetAlgebra, then, isn't it?
>>> Hmm, arguably. It's a shame that we won't be able to use it with
>>> things like `OptionSet`, though.
>> Why not?  That conforms to SetAlgebra.
> I mean that `OptionSet.RawValue` currently has to conform to
> `BitwiseOperations`, 

Actually it doesn't.  You just have to implement these yourself in that

  extension OptionSet where Self.RawValue : BitwiseOperations {
    convenience init()
    mutating func formUnion(_ other: Self)
    mutating func formIntersection(_ other: Self)
    mutating func formSymmetricDifference(_ other: Self)

> but would now need to conform to `BinaryInteger` (or a sub-protocol).

Does that limit you in some useful way?


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