fib.ml

(* fibonacci *)
let fib(x:int) =
  let rec fib_i(n, a, b) =
    if n = 1 || n = 2 then a
    else fib_i(n-1, a+b, a)
  in fib_i(x, 1, 1);;
(* 実行：
# #trace fib;;
fib is now traced.
# fib 4;;
fib <-- 4
fib --> 3
- : int = 3
*)