Initializing an array from sequence or by repeating an element is not implemented

Array initializers init<S>(S) and init(repeating: Array.Element, count: Int) don’t seem to be implemented:

  • Array(array[0 ... 3]) gives ‘Parameter should be labeled “of”’
  • [Int](0..<256) gives ‘No overloaded constructor with these parameters for type “Array<Int64!>”, best matching overload is “init(_ sequence: INSFastEnumeration) -> Array<Int64!>!”’, which in turn results in ‘parameter 1 is “Range” should be “INSFastEnumeration”’
  • [UInt8](repeating: 0, count: padding) gives “No matching overload”
  • etc.

hmm, I do see

    public init(sequence: ISequence<T>) {

on SwiftArray, in Swift Base Library ( Does that not do what you need? I’ll look at adding init(repeating: count).

Fwiw, contributions to SBL are appreciated :wink:


maybe this just needs to be renamed, to drop the external sequence: name prefix? Ranges should be sequences…

Ah yes, that must be it: dropping the prefix should work. Thanks for the GitHub link. You can expect a bunch of pull requests now. :slight_smile:

Oddly, I do see a convenience init that takes a sequence, w.o the prefix. weird that that didn’t get used. I;ll need to check more…


@mh, did you find out what is causing this? It still doesn’t work in Elements I just set out to implement all the parts I’m missing in SwiftBaseLibrary (including Array.contains), but they are all there. They just don’t work for some reason.

My apologies,. this had dropped ff my radar :(. Can you remind me what platform you’re using?

No worries. I’m using Toffee (macOS 10.14.2). I will target Island, but not until I can compile with Silver on macOS.

Ok, it does look like we have a couple compiler bugs here, what I can reproduce on .NET is:

let x = Array(array[0 ... 3]) // E122 Cannot instantiate abstract class "Array!"

(different/odd error, but definitively wrong)

let z = [UInt8](repeating: 0, count: 5) // E317 No overloaded constructor with these parameters for type "Array<UInt8>"

that one’s also wrong, as the .ctor is there.

I’ll log these two as compiler bugs.

as for the ranges, there are two issues, for one, the name-less .ctor that takes a sequence was not implemented for .NET (fixed); for another, Range does jot current;y implement the ISequence protocol, so it’s not directly compatible with that. I’ll fix this (needs some more work than I can do right this second), but this workaround works:

let s: ISequence<Int64> = (0..<256).GetSequence()
let y1 = [Int](s)


let y2 = [Int]((0..<256).GetSequence())

On macOS, slightly different results:

let x = Array(array[0 ... 3]) // E46 Unknown identifier "array"

kinda m makes sense now that I look at that closer. what’s that syntax supposed to be, array[0 ... 3]? this one works, instead:

let x = Array(array: [0 ... 3])

The other one

let z = [UInt8](repeating: 0, count: 5) // E317 No overloaded constructor with these parameters for type "Array<UInt8>" // E317 No overloaded constructor with these parameters for type "Swift.Array<Byte!>"

fails the same.

Oops. egg on face. that ctor was simply missing a public. fixed.

My bad: array was any array longer than four elements here, for example:

let array = [UInt8](0 ..< 8)

Thanks, logged as bugs://81651 for the Array(array...) issue

Ah. checking…

Apparently that [UInt8](0 ..< 8) doesn’t compile either (“No matching overload”).

that one gives me

let array = [UInt8]()

let x1 = Array(array[0 ... 3]) // E599 Parameter labels do not match. Parameter 1 is unlabeled, but should should be labeled "contentsOfURL" in call to "init(contentsOfURL url: NSURL) -> NSArray<id!>!"
let x2 = Array(array: [0 ... 3])

which seems correct (ignoring that it suggests the wrong overloaded .ctor). the parameter is named, array: should be needed?

Xcode does not like this:

let x2 = Array(array: [0 ... 3])

(Array does not have a constructor with named parameter array.) In any case, [0 ... 3] and array[0 ... 3] are sequences, so Array(sequence:) should work in Silver. Swift Base Library also has a convenience init without the prefix, but that doesn’t work yet.

The problem is arrays aren’t sequences on Cocoa, since we concerted the Array class to be a struct (on popular request), and structs cannot implement protocols (right now), that’s a platform limitation on Cocoa.

What I’ll do for now is add a name-less .ctor that takes arrays.

In Apple’s implementation, neither [0 ... 3] nor array[0 ... 3] is an array. The former is a ClosedRange and the latter is an ArraySlice, both of which are sequences.