A breakpoint can be modified to make it print an expression and its value when it is reached.
Again suppose that you have reached a breakpoint on the call to
as set in the example above. To make this breakpoint print, choose
from the Breakpoint Options menu, and enter a valid Lisp expression in the
tab of the Edit Breakpoint dialog, and click OK.
When the breakpoint is reached, the expression and its value are printed like this:
Stepper value (+ 4 4 4 4): 16
The Lisp expression is evaluated in the package where the stepped function was defined. Note that this package is displayed in the Printing tab of the Edit Breakpoint dialog.
If you check the Print without stopping option, then the above line is printed but the code continues to execute and does not stop at the breakpoint.
Note: you cannot currently access the values of local variables in the printed expression.
LispWorks IDE User Guide (Unix version) - 25 Nov 2011