Info: https://github.com/Kametrixom/The-Swift-Make-It-Compile-Challenge

Challenge3.swift

// This one is quite tricky

let returnN = getReturnN()

func availableToIntCollection<C: CollectionType where C.Generator.Element == Int>(c: C) {}

availableToIntCollection([1, 2, 3].lazy.map(returnN))


var a : Int { returnN (n: 3) }
var b : Int { return N(n: 3) }

It strikes me as strange that we can annotate a closure with @NoReturn when defining its type, but can't define such a closure directly; it must have a named function assigned to it instead. At least we can define nested functions:

func getReturnN() -> @noreturn (n: Int) -> Int {
    // Two n's are not needed; in fact, not even one is!
    // Only the parameter name in the return value matters.
    @noreturn func returnN(_: Int) -> Int {}
    return returnN
}