pga/pga.ml

open Types
open Stringify
open Parse

let main () =
  let usage status =
    prerr_endline ("usage: " ^ Sys.argv.(0) ^ " command [args]");
    prerr_endline "command:";
    prerr_endline "  help           show this help page";
    prerr_endline "  echo PROGRAM   pretty-print a program";
    prerr_endline "input program syntax:";
    prerr_endline "  - omit omega sign after closing parenthesis";
    prerr_endline "  - write dollar sign ($) instead of pound sign";
    exit status
  in

  let argc = Array.length Sys.argv in
  if argc = 1 then usage 1;

  begin
    try
      match Sys.argv.(1) with
      | "help" ->
        usage 0
      | "echo" when argc > 2 ->
        print_endline (string_of_program (parse_string Sys.argv.(2)))
      | _ ->
        usage 1
    with
    | ParseError msg ->
      prerr_endline ("parsing error: " ^ msg);
      exit 1
  end;

  exit 0

let () = main ()