on Sat Apr 16 2016, Thorsten Seitz <swift-evolution@swift.org> wrote:
>> Am 15.04.2016 um 23:19 schrieb Dmitri Gribenko via swift-evolution >> <swift-evolution@swift.org>: >> >> On Fri, Apr 15, 2016 at 1:30 PM, Stephan Tolksdorf <s...@quanttec.com> wrote: >>> On 2016-04-12 Dmitri Gribenko via swift-evolution wrote: >>>> > >>>> Not even to mention that >>>> indices are valid only in context of a particular collection instance, >>>> so in this model you could validate an index against one collection >>>> and use it with another one. >>> >>> >>> The proposal requires Index values to be Comparable. Does that mean that >>> indices from different collection instances should be comparable i.e. have a >>> strict total order? >> >> No, comparing indices from unrelated instances produces unspecified >> results (incl. traps). > > Path dependent types as used in Scala would allow making this > distinction type safe (see > http://docs.scala-lang.org/tutorials/tour/inner-classes or > http://danielwestheide.com/blog/2013/02/13/the-neophytes-guide-to-scala-part-13-path-dependent-types.html) > by allowing the index type to be rooted at the instance. Wouldn't that also rule out useful designs, as in those where indices into one collection are stored in another? > Are there any plans to adding path dependent types to Swift? I don't know of any, but that doesn't really mean much. -- Dave _______________________________________________ swift-evolution mailing list swift-evolution@swift.org https://lists.swift.org/mailman/listinfo/swift-evolution