Source file lib.ml

(** [fold (x::xs) z f] = [f x (fold xs z f)] **)
let fold l z0 f =
  let rec loop z = function
    | [] -> z
    | x::xs -> loop (f x z) xs
  in loop z0 (List.rev l)

(** [map [x; y; ...] f] = [f x; f y; ...] **)
let rec map l f =
  match l with
  | [] -> []
  | x::xs -> f x::map xs f