# List.map string_of_int [1; 2; 3]
- : string list = ["1"; "2"; "3"]

# List.map (function n -> Array.make n 3) [3; 4; 5];;
- : int array list = [[|3; 3; 3|]; [|3; 3; 3; 3|]; [|3; 3; 3; 3; 3|]]

# List.fold_left (fun a x -> a + x) 0 [2; 3; 5; 7; 11]  (* sum *);;
- : int = 28

# List.fold_left (fun a x -> a * x) 1 [2; 3; 5; 7; 11]  (* product *);;
- : int = 2310

# List.fold_left (fun l x -> List.map (function l -> x :: l) ([] :: l))
    [] [2; 3; 5; 7; 11];;    
- : int list list = [[11]; [11; 7]; [11; 7; 5]; [11; 7; 5; 3]; [11; 7; 5; 3; 2]]
  (* suffices of a list *)

(* welcome.ml *)

let print whatever =
  Printf.printf "Welcome to %s!!!\n" whatever

(* main.ml *)

Welcome.print "OCaml world"

ocamlopt -o main welcome.ml main.ml

(* Takeuchi's Tarai function *)

let rec t x y z =
  if x <= y then y
  else t (t(x - 1) y z) (t (y - 1) z x) (t (z - 1) x y)

let x, y, z = (14, 7, 0);;
Printf.printf "Takeuchi(%d, %d, %d) = ...%t" x y z flush;

$ ocamlc -o tak tak.ml
$ time ./tak
Takeuchi(15, 8, 0) = ... 15
./tak  72.69s user 0.27s system 99% cpu 1:13.56 total

$ ocamlopt -o tak tak.ml
$ time ./tak
Takeuchi(15, 8, 0) = ... 15
./tak  6.46s user 0.04s system 98% cpu 6.564 total