partitions

gistfile1.ml

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

let print_list f lst =
  print_string "[";
  List.iter (fun x -> (f x; print_string "; ")) lst;
  print_string "]";
  print_newline ();;

let rec parts_by_num n b =
  let _ = print_int n
  and _ = print_newline ()
  in
  
  if n = 0
  then
    [[]]
  else
    List.flatten(
      List.map
        (fun x ->
          List.map
            (fun l -> x :: l)
            (parts_by_num (n-x) x)
        )
        (range b n)
      );;

print_list (print_list print_int) (parts_by_num 4 1);;