(* Dumb Fibonacci microbenchmark in OCaml.  The interpreter invoked as

    time ocaml dumbfib.ml

says

    fib(40) = 102334155

in about 4.02–4.07 seconds on the same machine where dumbfib.S takes
683–686 milliseconds, a roughly 6× slowdown.  Compiling with ocamlc
gives about 3.90–3.92 seconds.  ocamlopt gives 0.724 seconds, about
a 6% slowdown.

*)

let rec fib n = if n <= 2 then 1 else fib (n-1) + fib (n-2)
  and n = 40
    in Printf.printf "fib(%d) = %d\n" n (fib n) ;;