;;; THE INTRO TO AI SHOW
;;; Summer Session I 1999
;;;
;;; DEMO:
;;; Collatz function
;;;
;;; NOTE:
;;; The function in question is defined in normal
;;; mathematical form in the class slides.
;;;
;;; Selmer Bringsjord
;;;;;;;;;;;;;;;;;;;;;;;;;;

;;; First, a simple example of loop.

(defun enumerate-bringsjords ()
  (let ((bringsjords 
         '(thor carl conrad olga alexander katherine erik kurt pam)))
    (loop
      (when (endp bringsjords) (return 'done))
      (print (first bringsjords))
      (format t "is a very smart person.")
      (setf bringsjords (rest bringsjords)))))

(defun enumerate-all-bringsjords ()
  (enumerate-bringsjords)
  (format t "~%... But SELMER is an outright genius."))


;;; Collatz's Problem used to show loop and then
;;; do-times.  Is this a total function on the natural numbers?

(defun mystery (n) 
  (loop (print n)
        (when (or (equal 0 n) (equal 1 n)) (return n))
        (if (evenp n) (setf n (/ n 2)) (setf n (+ 1 (* 3 n))))))
   
(defun mystery-loop (max)
  (dotimes (count max) (mystery count)))

(with-open-file (random-stream "chaotic-nums2" :direction :output)
    (print (mystery-loop 5) random-stream))