26.3.3 Side-effects of stepping

When the Stepper steps a definition for the first time, it evaluates it.

This will not normally alter the behavior of your program, but there are three situations where this will cause unexpected behavior:

• The code is loaded from a fasl file which is not compatible with the corresponding source file.
• The source relies on compile-time side-effects of forms preceding it in the file.
• The defining form has other side effects. This is unlikely to matter for simple definers such as defun and defmethod .

LispWorks IDE User Guide (Windows version) - 25 Nov 2011