(* You need the Benchmark module
   (http://www.bagley.org/~doug/ocaml/benchmark/). *)

let map' f l =  (* tail recursive version of map *)
  let rec aux acc = function
    | [] -> List.rev acc
    | hd :: tl -> aux (f hd :: acc) tl
  in
  aux [] l


let map2 f l = (* Crazy way... *)
  Array.to_list(Array.map f (Array.of_list l))

let () =
  let f x = succ x in (* simple fun, so its cost should be unimportant *)
  let bench n =
    let l = Array.to_list (Array.init n (fun x -> x)) in
    Printf.printf ">>> LIST LENGTH = %i\n" n;
    let res = Benchmark.throughputN 20
                [("List.map", List.map f, l);
                 ("tail_rec", map' f, l);
                 ("crazy", map2 f, l)
                ] in
    Benchmark.tabulate res in

  bench 100;
  bench 1000;
  bench 10_000;
  bench 100_000;
  bench 400_000