simple 'cat' command in O'Caml

cat.ml

(* cat.ml *)
(* simple cat command in O'Caml *)

open Sys
open Array
open List

let print_channel in_channel =
  let rec iter _ =
    print_endline (input_line in_channel);
    iter()
  in try iter () with
      End_of_file -> close_in in_channel

let cat =
  List.iter print_channel

let _ =
  match List.tl (Array.to_list Sys.argv) with
    | [] -> cat [stdin]
    | hd :: tl as filenames -> cat (List.map open_in filenames)