Rotate Array in Swift

Question

While exploring algorithms in Swift, couldn\'t find algorithm for array rotation in swift without using funcs shiftLeft / shiftRight.

C has

Answer 1

Why create a reverse function when we already have it in the Swift standard library? My solution (derived from Leo Dabus'):

extension Array {
    mutating func rotate(positions: Int, size: Int? = nil) {
        let size = size ?? count
        guard positions < count && size <= count else { return }

        self[0..