on Wed Apr 06 2016, Erica Sadun <swift-evolution@swift.org> wrote: >> On Apr 6, 2016, at 2:17 PM, Xiaodi Wu <xiaodi...@gmail.com> wrote: >> Prohibiting StrideTo with floating-point ranges altogether would be >> distressing. IMO, it's plenty distressing that backwards >> floating-point StrideTo as it currently exists might go away. > > I wouldn't suggest doing so. I'm just saying that for a half-open interval, > there is no max value > so it makes no sense mathematically to have a first value and a > negative step.
I don't agree. It seems to me that striding downwards over a half-open range r should always begin with r.upperBound - s (modulo any necessary adjustments to avoid FP error), where -s is the stride amount. Why is that mathematical nonsense? Another point to consider: striding is also a sensible operation over collections, and some ranges are collections. The stride semantics must coincide in those cases. I expect that constraint narrows down the reasonable semantic choices considerably. > You're not so restricted with: > > * positive steps > * closed intervals > > -- E > > _______________________________________________ > swift-evolution mailing list > swift-evolution@swift.org > https://lists.swift.org/mailman/listinfo/swift-evolution -- Dave _______________________________________________ swift-evolution mailing list swift-evolution@swift.org https://lists.swift.org/mailman/listinfo/swift-evolution
