pga/pga.ml

open Types
open Stringify

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 TERM   pretty-print a program";
    prerr_endline "input program syntax:";
    prerr_endline "  - write star (*) instead of omega sign";
    prerr_endline "  - write dollar sign ($) instead of pound sign";
    prerr_endline "";
    prerr_endline "A TERM argument may also be omitted and passed on stdin";
    prerr_endline "instead for convenient use of UNIX pipes";
    exit status
  in

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

  let input_term i =
    let lexbuf =
      if argc > i
        then Lexing.from_string Sys.argv.(i)
        else Lexing.from_channel stdin
    in
    Parse.parse_with_error lexbuf
  in

  begin
    try
      match Sys.argv.(1) with
      | "help" ->
        usage 0
      | "echo" ->
        print_endline (string_of_program (input_term 2))
      | _ ->
        usage 1
    with
    | FatalError msg ->
      prerr_endline msg;
      exit 1
  end;

  exit 0

let () = main ()