;;Functions to help test-dotted-lists
;;The below function is taken from the text book, page 49
(defun proper-listp (x);a proper list is nill, or a cons cell whoes cdr is a proper list.
  (or (null x);if null
    (and (consp x);or if it is a conscell
      (proper-listp (cdr x)))));whoes cdr is a proper list

(defun dotted-listp (x)
  (not (proper-listp x)));if a list is not propper, then its dotted

;;Chapter 3, Test 9, Page 49
(deftest test-dotted-lists ()
  (check
    (dotted-listp (cons 1 (cons 2 (cons 3 4))));last conscell is dotted
    (dotted-listp (cons (list 1 2 3) (cons 1 2)));again, last conscell is dotted
    (proper-listp (cons 1 (cons 2 (cons 3 (cons 4 nil)))));the nil at the end of the conscell chain makes it proper
    (proper-listp (list 1 2 3 4))));list always returns a proper list