> On Jun 2, 2017, at 2:11 AM, Jaden Geller <jaden.gel...@gmail.com> wrote: > > Comments inline. > >> On Jun 1, 2017, at 10:49 PM, Daryle Walker via swift-evolution >> <swift-evolution@swift.org <mailto:swift-evolution@swift.org>> wrote: >> >> Current array literal syntax (i.e. “[a, b, c]”) works for dense and/or >> linear arrays, but isn’t so great later on when we add fixed-size arrays and >> the defined (non-zero) elements are sparse and/or the array is >> multi-dimensional (not nested). In these cases I’m thinking of leading each >> element with its coordinate: >> >> … 6: a, … // complete value, linear array > > You can already do this with a dictionary since a Int can be used as the key > type. > >> … (1, 2): b, … // complete value, multi-dimensional array > > This would be possible if tuples of hashable types were considered hahable. > Right now, you could define some point type. > >> … (let x, let y) where y % 2 == 0: c * y + x, … // pattern of qualifying >> coordinates > > You can build this sort of thing using an initializer that takes a function. > You wouldn’t get this sugar, but I don’t think it is necessary. > >> … default: d, … // when no other initializer covers an element (Use “_” >> instead?) > > This one is a bit harder. I think it would be reasonable for there to exist > some subtype of the dictionary literal type that also included information > about a default value, but I think this should be motivated by the Swift > standard library (e.g. a defaultable dictionary type). > > Right now, you can just make literal syntax default to a `nil` default value, > and then you can define a function that nil-coalesces the default value. This > is definitely less elegant, but I don’t think it matters a whole lot. > ``` > Sparse([1: “foo”, 5: “bar”, 100: “baz”], default: “”) > ```
I’m not asking how to do this in current Swift with current types, but fixed-sized arrays in a future Swift. I’m asking if this mixing of array- and dictionary-literals for these advanced-array literals would be too hard for compiler implementors to implement. — Daryle Walker Mac, Internet, and Video Game Junkie darylew AT mac DOT com
_______________________________________________ swift-evolution mailing list swift-evolution@swift.org https://lists.swift.org/mailman/listinfo/swift-evolution
