: insertion-sort ( seq -- )
    1
    over length 1-
    [
        2dup swap nth 2over
        [   3dup
            [ 2nip 0 > ]
            [ 1- swap nth < ]
            2array 3&& ]
        [
            dup 1- pick nth 2over swap set-nth
            1-
        ] while
        swap set-nth
        1+
    ] times
    2drop
;