Developing Programs Interactively

It is very rare for a programmer to get everything right the first time round. Typically developing programs is a cycle of editing the programming file, testing the program, finding some problems, editing the program file, etc.

• To edit the file, display it in a buffer. Use C-x 4 f with the filename if you open the file for the first time (C-x 5 f if you are running Emacs under OpenWindows), or C-x 4 b/C-x 5 b if you are revisiting the file (with OpenWindows Emacs, you can also use the mouse to make the program file the current one, if the frame is visible on the screen).
• Change the file, and remember to save the changes--C-x C-s--or else the interpreter will load the same version of the file as you used the last time.
• Go back to the window where the interpreter is running (unless you are starting it for the first time of course)! Use C-x 4 b/C-x 5 b and state that you want the buffer *prolog* (again, if the frame with the interpreter is visible, you can use the mouse).
• Reload the file into the interpreter with consult.