public void readEvalPrint() {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		while (true) {
			String line = "";
			try {
				System.err.print(" >: ");
				line = br.readLine();
			} catch (IOException e) {
				System.err.println("Error reading from input.");
				continue;
			}
			String[] cmd = null;
			try {
				cmd = InputLineParser.parseInputLine(line);
			} catch (ParseException e) {
				System.err.println(e.getMessage());
				continue;
			}
			if (cmd.length == 0) {
				// The user just pressed enter
				continue;
			}

			Command command = this.commands.get(cmd[0]);

			if (command == null) {
				System.err.println("Command not recognized.");
			} else {
				command.execute(cmd);
			}

		}
	}