[swift-evolution] [pitch] Comparison Reform

[Xiaodi Wu]

Jaden, the proposal literally says that a compiler feature named
"@_implements" is necessary for the proposed design to work. You can see
WIP for that feature in the apple/swift repo.


On Thu, Apr 13, 2017 at 19:55 Jaden Geller <jaden.geller at gmail.com> wrote:

>
> On Apr 13, 2017, at 5:18 PM, Xiaodi Wu via swift-evolution <
> swift-evolution at swift.org> wrote:
>
> Actually, the fact that this behavior cannot even be achieved without
> currently non-existent compiler features means that it is not possible to
> understand what's truly going on without reading *this document*, after
> mastering *both* IEEE floating point *and* Swift
> generics/protocols/extensions/static vs. dynamic dispatch. All to use `==`
> correctly. Which is to say, most people will simply not even know if they
> happen to be using the `==` they did not intend to use.
>
>
> If I understand correctly, I think you’re mistaken. The compiler already
> selects overloads based on generic context. If `T: FloatingPoint`, then
> it’ll choose the `==` with signature `<T: FloatingPoint> (T, T) -> Bool`.
> If `T: Equatable`, then it’ll choose the `==` with signature `<T:
> Equatable> (T, T) -> Bool`. No new compiler features are necessary for this
> specific behavior.
>
> Cheers,
> Jaden Geller
>
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