Puck language sample code.

insertion_sort.p

\   INSERTION_SORT
\ 
\   Sort INPUT into ascending order as determined by the LESS_THAN binary
\   predicate. This sorting algorithm is stable.

Let insertion_sort less_than input.
    (list.fold_left
        Func sorted elem.
            Loop left right.
                (Init `nil sorted)      \ Provides args for first iteration.
                Match right
                | `nil (list.reverse (elem:left))
                | `cons.{elem' right'}
                    If (less_than elem elem')
                        (list.reverse_append left (elem:right))
                        (Recur (elem':left) right')
                ;
        `nil
        input)

\   Some tests.

(list.map (insertion_sort (<))
    [List
        [List]          \ Empty list. Equivalent to `nil.
        [List 1 2 3]
        [List 2 2 2]
        [List 3 2 1]])