A simple OCaml program using Async

add_all.ml

open Core
open Async

let add_all file =
  Reader.file_contents file >>= fun contents ->
  let ls  = String.split_lines contents in
  let ss  = String.split_on_chars (String.concat ls) ~on:[','] in
  let ns  = List.map ss ~f:Int.of_string in
  let sum = List.fold_left ns ~init:0 ~f:(+) in
  printf "%d\n" sum;
  return ()

let () =
  Command.async_spec
    ~summary:"Adds it all!"
    Command.Spec.(empty +> anon ("file" %: string))
    (fun file () -> add_all file)
  |> Command.run