;; Two functions written live in the lecture on 5/10/2007

;; The variable names were chosen by the class. 

;; Note the use of a helper function


;; A function which reverses a list

;; so rev '(1 2 3) gives us '(3 2 1)

(defun rev (mylist)
       (if (null mylist)
       	   nil
	   (snoc (car mylist) (rev (cdr mylist)))

       )
)


;; A helper function which is a bit like cons but puts the element
;; at the end instead of the beginning
;; So (snoc 1 '(2 3)) gives us '(2 3 1)

(defun snoc (um err)
       (if (null err)
       	   (cons um '())
	   (cons (car err) (snoc um (cdr err)))
       )
)