module Combinatoire exposing(choices)

{-|

interleave 4 [1,2]
 => [[4,1,2],[1,4,2],[1,2,4]]



subs[4,1,2]
=> [[],[2],[1],[1,2],[4],[4,2],[4,1],[4,1,2]]    




perms[4,1,2]
[[4,1,2],[1,4,2],[1,2,4],[4,2,1],[2,4,1],[2,1,4]]



    split[1,2,3,4]
    [([1],[2,3,4]),([1,2],[3,4]),([1,2,3],[4])]



-}


interleave : Int ->  List Int -> List(List Int)