Insertion Sort algorithm written in Swift

insertion-sort.playground

typealias ArrayInt = Array<Int>

func lt(a: Int, b: Int) -> Bool {
    return a < b
}
func gt(a: Int, b: Int) -> Bool {
    return a > b
}

func insertionSort(arr: ArrayInt, comp: (Int, Int) -> Bool) -> ArrayInt {

    var key = 0
    var j = 0
    var i = 0
    
    // create a copy of the array to work with
    var new_arr = arr

    for j = 1; j < new_arr.count; ++j {
        key = new_arr[j]
        i = j - 1
        
        //while i >= 0 && new_arr[i] > key {
        
        while i >= 0 && comp(new_arr[i], key) {
            new_arr[i + 1] = new_arr[i]
            i = i - 1
        }
        new_arr[i + 1] = key
    }
    return new_arr
}

var myArr: [Int] = [31, 41, 59, 26, 41, 58]
insertionSort(myArr, gt)