gistfile1.ml

let rec map f x y =
    match (x,y) with
      ([],_) | (_,[]) -> failwith "list do not have same length"
    | ([a],[b]) -> [f a b]
    | (h1::t1,h2::t2) -> (f h1 h2)::(map f t1 t2)
;; (* map *)

open Printf;;

Printf.printf "%d\n" (map (fun x y -> x * y) [1;2;3;4;5] [1;2;3;4;5]);;

(* line 10, characters 21-69:
   Error: This expression has type int list but is here used with type int *)