Today's Swift WTF - Arrays

array.swift

#!/usr/bin/env xcrun swift

func info<T>(x: T) {
    println("\(x) is a \(_stdlib_getDemangledTypeName(x))")
}


let array = [0, 1, 2] // appending 'as AnyObject' here yields a compiler error
info(array)

import Foundation

let objc_array: AnyObject = [0, 1, 2] as AnyObject
info(objc_array)

// comparing different array types => compiler error as well
//let equal = objc_array == array

Output:

[0, 1, 2] is a Swift.Array
(
    0,
    1,
    2
) is a Swift._NSSwiftArrayImpl

or in other words, ObjC compatibility of arrays is achieved by having two implementations, chosen by the context they are used in and by the presence of a Foundation import.