Function to shuffle an array

shuffle.dwl

%dw 2.0

fun splice(arr: Array, index: Number) =
    if (index == 0) arr[1 to -1]
    else (arr[0 to index-1] default []) ++ (arr[index+1 to -1] default [])

fun shuffle(arr: Array) =
    (((0 to sizeOf(arr)-1) as Array) reduce (i, s = {res:[], items: arr}) -> do {
        var ri = floor(random() * sizeOf(s.items))
        ---
        {
            res: s.res << s.items[ri],
            items: s.items splice ri
        }
    }).res