> * Operations that depend on sorted-ness and use binary predicates should > not be available on all Collections; they're too easy to misuse, > they're hard to name well, and as Nicola Salmoria has noted, they > would not make any sense at all for a Set<T>. > > * They should be scoped to a kind of collection that bundles > the predicate with the elements, e.g. > > let x = Sorted([3, 4, 1, 5, 2], >) // stores a sorted copy of the > array > let y = Sorted(preSorted: 0..<100, <) // stores a copy of the range > > Maybe there should also be protocols for this; CountableRange<T> would > already already conform to the immutable version. We might want a > mutable form of the protocol for sorted collections with > insertion/removal methods. This whole area needs more design.
I agree with both of these statements, but not with your conclusion. There are three classes of collections: 1) Those which are always sorted, like a SortedSet. 2) Those which may or may not be sorted, like an Array. 3) Those which are never sorted, like a Set. These APIs are useless on a #3, but #2 is still a valuable use case to support. In particular, it's quite common to use sorted `Array`s, and these APIs would help you do that. What I might consider doing is tying this to `RangeReplaceableCollection`. That protocol is applied only to types which allow insertion at arbitrary indices, which is a good, though not perfect, proxy for types which might allow you to manually maintain a sort order. `Array`, `ArraySlice`, `ContiguousArray`, and the mutable `String` views would get these methods, while `Set` and `Dictionary` would not. -- Brent Royal-Gordon Architechies _______________________________________________ swift-evolution mailing list swift-evolution@swift.org https://lists.swift.org/mailman/listinfo/swift-evolution
