open Printf

module IntSet =
  Set.Make (
      struct
        type t = int
        let compare = compare
      end)

module IntSetHash =
  Hashtbl.Make (
      struct
        type t = IntSet.t
        let equal = IntSet.equal
        let hash s = IntSet.fold (fun x a -> a + x) s 0
      end)

let rec interval a b =
  if a >= b then
    []
  else
    a::(interval (a+1) b)

let rec insert x ys =
  match ys with
    [] -> [[x]]
  | y::ys' ->
     (x::ys)::(List.map (fun rs -> y::rs) (insert x ys'))

let rec perm xs =
  match xs with
    [] -> [[]]
  | x::xs' ->
     List.flatten (List.map (insert x) (perm xs'))

let test create reg iter length =
  let ht = create 0 in
  List.iter
    (fun xs ->
      let s = IntSet.of_list xs in
      reg ht s true)
    (perm (interval 0 5));
  printf "----------------------------------------\n";
  printf "%d\n" (length ht);
  iter
    (fun s _ ->
      printf "{ ";
      IntSet.iter
        (fun x -> printf "%d " x)
        s;
      printf "}\n")
    ht

let () = test Hashtbl.create Hashtbl.replace Hashtbl.iter Hashtbl.length
let () = test IntSetHash.create IntSetHash.replace IntSetHash.iter IntSetHash.length