open Printf

let error_to_string e =
  try raise e with
  | Parser.Expected t -> sprintf "expected %s" t
  | Parser.Unexpected_token t -> sprintf "unexpected token \"%s\"" t
  | Failure f -> f
  | Division_by_zero -> "cannot divide by zero"
  | _ -> raise e

let print_error e =
  printf "error: %s\n" @@ error_to_string e

(* simple REPL *)
let rec repl () : unit =
  printf "> ";
  let line = read_line () in
  if line <> "quit" then begin
    try
      line
      |> Lex.tokenize
      |> Parser.parse
      |> Eval.eval
      |> Ast.typ_to_string
      |> printf "%s\n"
    with
    | e -> print_error e;
    repl ()
  end

let () = repl ()