gistfile1.ml

let fib n =
  (let rec iter n a b =
    (if ((=) n 0)
      then a
      else (iter ((-) n 1) b ((+) a b)))
    in (iter n 0 1))

gistfile2.scm

(define (fib n)
  (define (iter n a b)
    (if (= n 0)
      a
      (iter (- n 1) b (+ a b))))
  (iter n 0 1))