> On Apr 6, 2016, at 2:25 PM, Dave Abrahams via swift-evolution > <swift-evolution@swift.org> wrote: > > > on Wed Apr 06 2016, Erica Sadun <erica-AT-ericasadun.com> wrote: > >> On Apr 6, 2016, at 3:05 PM, Dave Abrahams via swift-evolution >> <swift-evolution@swift.org> wrote: >> >> on Wed Apr 06 2016, Xiaodi Wu <xiaodi.wu-AT-gmail.com> wrote: >> >> On Wed, Apr 6, 2016 at 3:28 PM, Dave Abrahams via swift-evolution >> <swift-evolution@swift.org> wrote: >> >> You if you need to represent `<..` intervals in scientific computing, >> that's a pretty compelling argument for supporting them. >> >> I'd like to be able to represent any of those as >> Intervals-which-are-now-Ranges. It makes sense to do so >> because >> the >> things I want to do with them, such as clamping and testing if >> some >> value is contained, are exactly what Intervals-now-Ranges >> provide. >> Looking around, it seems many other languages provide only >> what >> Swift >> currently does, but Perl does provide `..`, `..^`, `^..`, and >> `^..^` >> (which, brought over to Swift, would be `...`, `..<`, `<..`, >> and >> `<.<`). >> >> Do we need fully-open ranges too? >> >> I haven't encountered a need for open ranges, but I would expect that >> other applications in scientific computing could make use of them. >> I rather like Pyry's suggestions below. >> >> Below? >> >> Logically in time below. > > Oh! In my application, time flows downward. > >> >> I believe the following is a valid conversion of the Xiaodi Wu below into the >> Dave A domain. >> >> On Apr 6, 2016, at 2:29 PM, Pyry Jahkola via swift-evolution >> <swift-evolution@swift.org> wrote: >> >> I think a sensible specification would be that with a positive step size, >> the count starts from the lower bound, and with a negative one, it starts >> from the upper bound (inclusive or exclusive). Thus, the following >> examples >> should cover all the corner cases: >> >> (0 ... 9).striding(by: 2) == [0, 2, 4, 6, 8] >> (0 ..< 9).striding(by: 2) == [0, 2, 4, 6, 8] >> (0 <.. 9).striding(by: 2) == [2, 4, 6, 8] >> (0 <.< 9).striding(by: 2) == [2, 4, 6, 8] >> >> (0 ... 9).striding(by: 3) == [0, 3, 6, 9] >> (0 ..< 9).striding(by: 3) == [0, 3, 6] >> (0 <.. 9).striding(by: 3) == [3, 6, 9] >> (0 <.< 9).striding(by: 3) == [3, 6] >> >> (0 ... 9).striding(by: -2) == [9, 7, 5, 3, 1] >> (0 ..< 9).striding(by: -2) == [7, 5, 3, 1] >> (0 <.. 9).striding(by: -2) == [9, 7, 5, 3, 1] >> (0 <.< 9).striding(by: -2) == [7, 5, 3, 1] >> >> (0 ... 9).striding(by: -3) == [9, 6, 3, 0] >> (0 ..< 9).striding(by: -3) == [6, 3, 0] >> (0 <.. 9).striding(by: -3) == [9, 6, 3] >> (0 <.< 9).striding(by: -3) == [6, 3] > > These all look reasonable to me.
Agreed. – Steve _______________________________________________ swift-evolution mailing list swift-evolution@swift.org https://lists.swift.org/mailman/listinfo/swift-evolution