DrScheme is a popular Scheme development system created by the PLT group, now at Northeastern University. Using DrScheme is similar to having two emacs windows present, one containing the program being written and the other containing a running Scheme process (see below). Think of the top window as containing the current program. Any time you click on the Execute button the entire top window is evaluated. You can save anything you type there using the File menu. DrScheme also provides some useful debugging tools.