3.3.3 Function Names

If a function is defined by defun, labels, or flet, then the debugger will print the actual function name after the open parenthesis, like:

(STRING-UPCASE "test case" :START 0 :END NIL)
((SETF AREF) #\a "for" 1)

Otherwise, the function name is a string, and will be printed in quotes:

("DEFUN MYFUN" BAR)
("DEFMACRO DO" (DO ((I 0 (1+ I))) ((= I 13))) NIL)
("SETQ *GC-NOTIFY-BEFORE*")

This string name is derived from the defmumble form that encloses or expanded into the lambda, or the outermost enclosing form if there is no defmumble.