Why not have them return a `Bool?`? If both arguments are non-nil, it can return the results of the comparison, otherwise it can return nil.
- Dave Sweeris > On Jul 7, 2016, at 16:37, Jacob Bandes-Storch via swift-evolution > <[email protected]> wrote: > > These operators cause some potential for confusion: > > public func <<T : Comparable>(lhs: T?, rhs: T?) -> Bool > public func ><T : Comparable>(lhs: T?, rhs: T?) -> Bool > public func <=<T : Comparable>(lhs: T?, rhs: T?) -> Bool > public func >=<T : Comparable>(lhs: T?, rhs: T?) -> Bool > > 1. The meaning of T? < T? is not immediately obvious (Why is nil < .some(x) > for any x? Personally, my intuition says that Optional should only provide a > partial order, with .none not being ordered w.r.t. .some(x).) > > 2. Even if the meaning is understood, it can be surprising when the (T?, T?) > -> Bool version is used instead of (T, T) -> Bool. > > Prior discussion: > - http://thread.gmane.org/gmane.comp.lang.swift.devel/2089 > - http://thread.gmane.org/gmane.comp.lang.swift.evolution/10095 > - rdar://16966712&22833869 > - Replies to https://twitter.com/jtbandes/status/646914031433871364 > > In the swift-dev thread from May, Chris said: > >>> One of the ideas that Joe Pamer has been discussing is whether the implicit >>> promotion from T to T? should be disabled when in an operator context. >>> Doing so would fix problems like this, but making the code invalid. > > A change like this would be source-breaking, so if the core team has > recommendations for how to handle these issues, now is probably the time to > get it done. > > Jacob > _______________________________________________ > swift-evolution mailing list > [email protected] > https://lists.swift.org/mailman/listinfo/swift-evolution
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