In the section An Informal Introduction to Common Lisp, there is no proper introduction to defvar or defparameter before setf. This leads to undefined variable errors which might confuse new learners. Please include variable definitions in your examples and explain them properly:
(defvar width)
(defvar height)
(setf width 20)
(setf height (* 5 9))
(* width height)
(defvar tax)
(defvar price)
(setf tax (/ 12.5 100))
(setf price 100.50)
(* price tax)
In the section An Informal Introduction to Common Lisp, there is no proper introduction to
defvarordefparameterbeforesetf. This leads toundefined variableerrors which might confuse new learners. Please include variable definitions in your examples and explain them properly: