Why no Data.init(immutableBytesNoCopy:...)?

[Karl]

@tera

because that's what I actually meant. i.e. the main currency type, expressible with [Int], etc, in that pseudo code is a protocol, not a concrete type. This might or might not change your answer.

Perhaps this is not the swift way.. For example StringProtocol is even discouraged for new conformances. And I can't pass some custom collection ("RandomAccessCollection of Int elements") to a function that has [Int] argument (this would be cool IMHO).

[Int] is just sugar for Array<Int>, and changing that would be massively source-breaking.

I agree that generic functions are much more awkward to write, which is why the current efforts to improve generics syntax are so important. For example:

• SE-0341: Opaque Parameter Declarations

• [Pitch 2] Light-weight same-type requirement syntax

But the syntax is only part of the problem; the other part is gaps in capabilities. It seems like those are also being addressed, so the overall generics model is becoming much more usable and complete.