Funktionen und Kontrollfluss

let quadrat x = x * x
let addiere a b = a + b
let begruesse name = "Hallo, " ^ name ^ "!"

let () =
  Printf.printf "%d %d\n" (quadrat 7) (addiere 3 4);
  print_endline (begruesse "Mia");
  (* partielle Anwendung *)
  let plus10 = addiere 10 in
  Printf.printf "%d\n" (plus10 5);
  (* anonyme Funktionen *)
  let verdopple = fun x -> x * 2 in
  Printf.printf "%d\n" (verdopple 21);
  (* Funktionen als Argumente *)
  let wende_zweimal f x = f (f x) in
  Printf.printf "%d\n" (wende_zweimal (fun n -> n + 3) 10)

let vorzeichen n = if n > 0 then "positiv" else if n < 0 then "negativ" else "null"

let maximum a b = if a > b then a else b

let () =
  List.iter (fun n -> Printf.printf "%d: %s\n" n (vorzeichen n)) [5; -2; 0];
  Printf.printf "%d\n" (maximum 3 9);
  let alter = 20 in
  let status = if alter >= 18 then "volljährig" else "minderjährig" in
  print_endline status

let rec fakultaet n = if n <= 1 then 1 else n * fakultaet (n - 1)

(* endrekursiv: Akkumulator, kein wachsender Stack *)
let fib n =
  let rec schritt a b i = if i = 0 then a else schritt b (a + b) (i - 1) in
  schritt 0 1 n

let rec ggt a b = if b = 0 then a else ggt b (a mod b)

let () =
  Printf.printf "%d\n" (fakultaet 10);
  Printf.printf "%d\n" (fib 40);
  Printf.printf "%d\n" (ggt 48 18)

let () =
  for i = 1 to 5 do Printf.printf "%d " i done;
  print_newline ();
  for i = 5 downto 1 do Printf.printf "%d " i done;
  print_newline ();
  let zaehler = ref 0 in
  while !zaehler < 3 do
    Printf.printf "Durchlauf %d\n" !zaehler;
    incr zaehler
  done;
  let summe = ref 0 in
  for i = 1 to 100 do summe := !summe + i done;
  Printf.printf "%d\n" !summe

let zahlwort = function
  | 0 -> "null"
  | 1 -> "eins"
  | 2 -> "zwei"
  | n when n < 0 -> "negativ"
  | _ -> "viele"

let ist_vokal c = match c with
  | 'a' | 'e' | 'i' | 'o' | 'u' -> true
  | _ -> false

let () =
  List.iter (fun n -> print_endline (zahlwort n)) [0; 2; -5; 99];
  Printf.printf "%b %b\n" (ist_vokal 'e') (ist_vokal 'x');
  let (a, b) = (1, "x") in
  Printf.printf "%d %s\n" a b