(* Ask for the user name and answer hello. *)
Definition your_name (argv : list LString.t) : C.t System.effect unit :=
  do! System.log (LString.s "What is your name?") in
  let! name := System.read_line in
  match name with
  | None => ret tt
  | Some name => System.log (LString.s "Hello " ++ name ++ LString.s "!")
  end.