Changing the default CMUCL Prompt

The default CMUCL prompt is a fairly basic *. You can use the *PROMPT* variable to customize this prompt, either by setting it to a constant string, or by setting it to a function which will be called each time the prompt is displayed.

The following code demonstrates how to make CMUCL print the current package in the prompt.

   (in-package :cl-user)

   (defvar *last-package* nil)
   (defvar *cached-prompt*)

   (defun my-prompt ()
     (unless (eq *last-package* *package*)
       (setf *cached-prompt*
             (concatenate 'string (or (first (package-nicknames *package*))
                                      (package-name *package*))
                          "> "))
       (setf *last-package* *package*))
     *cached-prompt*)

   (setf lisp::*prompt* #'my-prompt)

If you wish to change the debugger's prompt (which defaults to something like 0] , where 0 indicates the number of recursive debuggers you have entered), there is a similar variable named DEBUG:*DEBUG-PROMPT*. Your function should print a string to *DEBUG-IO*.