LispForum

Thank you for the answer. My next question is, what is the general syntax of setf expander function definitions (google doesn't seem to help me with this) ?

Problem: (defun proba1 (li) (first (second li))) (defparameter li (list 1 (list 2) 3)) (setf (first (second li)) 1) ( setf (proba1 li) 1) ; result is an error The question is, how can the last command cause an error, when the one before it does not, and it does the same thing (but trough a function) ?