dc-mak

/* Imperative for-loop for factorial:
      ---------------------------------
      int factorial(int n)
      int result = 1
      for (int i = 2; i <= n; i = i + 1)
        result = result * i
      return result
   */
/* Transformation of for-loop into recursive function:
   --------------------------------------------------

dc-mak

let id = x => x;
let just = (y, _) => y;
let (+) = (f, g, x) => f(x) +. g(x);
let (-) = (f, g, x) => f(x) -. g(x);
let ( * ) = (f, g, x) => f(x) *. g(x);
let (@) = (f, g, x) => f(g(x));
let sq = id * id;
let f = id + sin * (cos @ sq) - just(3.);

/* Outside Inwards */

dc-mak

let directSumFrom1To = (n: int): int => n * (n + 1) / 2;
let directSumFrom1To: int => int = n => n * (n + 1) / 2;
let directSumFrom1To = n => n * (n + 1) / 2;

/* Step 1 */
/*
 * let choose_from = (k, n) =>
 *   choose_from(k - 1, n - 1) + choose_from(k, n - 1);
 */

dc-mak

(* helper functions for performance test *)

(* test one operation c times, output the mean time *)
let test_op s c op =
  let ttime = ref 0. in
  for i = 1 to c do
    Gc.compact ();
    let t0 = Unix.gettimeofday () in
    let _ = op () in
    let t1 = Unix.gettimeofday () in