Some TextMate automations interact with the user via GUI dialog boxes they display. Others show the user a web page with links that can trigger actions. We will take the road less traveled, though, and ask TextMate to respond to normal typing operations, turning it into a semi-interactive environment. This wouldn't be ideal for all commands, but it could be a useful technique for creating tools like a TextMate-savvy IRb (Interactive Ruby) clone or the shell worksheets some other editors have. It also makes fun calculators.