Getting the element count of a tuple in Swift by using variadic generics.

TupleCount.swift

// Overload for tuple values.
func tupleLength<each T>(_ tuple: (repeat each T)) -> Int {
    var count = 0
    for _ in repeat (each tuple) {
        count += 1
    }
    return count
}

tupleLength(()) // → 0
tupleLength(("A")) // → 1
tupleLength((1, 2, 3)) // → 3
tupleLength((1, "A", Void(), false)) // → 4

// Overload for tuple types.
func tupleLength<each T>(_: (repeat each T).Type) -> Int {
    var count = 0
    for _ in repeat (each T).self {
        count += 1
    }
    return count
}

tupleLength(Void.self) // → 0
tupleLength((Int).self) // → 1
tupleLength((String, String, String).self) // → 3
tupleLength((Int, String, Void, Bool).self) // → 4
let tupleType = (Int, String, Void, Bool).self
tupleLength(tupleType) // → 4