open Sys;;

let rec repeat chr times =
        match times with
                | 0 -> ()
                | _ -> print_string chr; repeat chr (times-1)
;;

let print_entry path level =
        repeat " " level;
        print_string ("| " ^ path ^ "\n")
;;

let process root =
        let rec sub_process path level =
                Array.iter (fun x -> match Sys.is_directory (path ^ "/" ^ x) with
                                | true -> print_entry x level;sub_process (path ^ "/" ^ x) (level+4)
                                | false -> print_entry x level
        ) (Sys.readdir path)
        in
        sub_process root 0
;;

let argc = Array.length Sys.argv in
match argc with
        | 1 -> print_string "Not enough arguments ! (1 needed)\n"
        | 2 -> process Sys.argv.(1)
        | _ -> print_string "Too many arguments ! (1 needed)\n"