(* while (p) do { ... } *)

let rec while_loop p f x =
  if (p x) then while_loop p f (f x) else x ;;

(* repeat { ... } until (p) *)

let rec repeat_loop p f x =
  let fx = f x in
    if (p fx) then fx else repeat_loop p f fx ;;

(* Funktionen testen *)

while_loop  (fun x -> x < 10000) (fun y -> y+5) 5 ;;
repeat_loop (fun x -> x > 10000) (fun y -> y+5) 5 ;;

(*
   val while_loop : ('a -> bool) -> ('a -> 'a) -> 'a -> 'a = <fun>
   val repeat_loop : ('a -> bool) -> ('a -> 'a) -> 'a -> 'a = <fun>
   - : int = 10000
   - : int = 10005
*)