> 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. Are there any plans to adding path dependent types to Swift? -Thorsten _______________________________________________ swift-evolution mailing list swift-evolution@swift.org https://lists.swift.org/mailman/listinfo/swift-evolution