fix.ml

module LazyFix = struct
  let rec fix f = f (lazy (fix f))

  let f_open = fun clo (x : int) ->
    if x <= 0 then x else (snd (Lazy.force clo)) (x - 1)
  let g_open = fun clo (x : int) ->
    if x <= 0 then x else (fst (Lazy.force clo)) (x - 1)

  let clo = fix (fun clo -> f_open clo, g_open clo)

  let f = fst clo
  let g = snd clo
end