(* 
 * consAllk needs to be defined for these to work
 * I put this in a separate file, but you can
 * just copy in your implementation and remove
 * the line below 
 *)
use "consAllk.sml";

fun appendAll []     = []
  | appendAll (x::xs) = x @ (appendAll xs);

fun infiltrate x []      = [[x]]
  | infiltrate x (y::ys) =
      (x::y::ys) :: (consAllk y (infiltrate x ys));

fun perms []      = [[]]
  | perms (x::xs) = appendAll (map (infiltrate x) (perms xs));