sumup.ml

let process filename =
  let ic = open_in filename in

  (* get list of floats from the file *)
  let rec read_one_line () = 
    try 
      Some 
      ( input_line ic 
        |> String.split_on_char ',' 
        |> List.map (fun s -> s |> String.trim |> float_of_string) )
    with
      End_of_file -> 
        close_in ic;
        None
  in

  (* iterating reading from file *)
  let rec next sum_ls =
    match read_one_line () with
    | Some ls -> 
        next (List.map2 ( +. ) sum_ls ls)
    | None ->
        sum_ls
  in

  (* read the first line *)
  match read_one_line () with
  | None -> (* exit if the first line is not found *)
      () 
  | Some ls -> (* process the first line *)
      next ls |> List.map (string_of_float) |> String.concat "," |> print_endline

let () =
  if Array.length Sys.argv < 2 then
    print_endline "Exactly one filename must be given." 
  else
    process Sys.argv.(1)