; function plays Towers of Hanoi Game
; Input is the size of of the tower to be
; moved, the peg where the disks are located,
; the peg where the disks are to be moved to,
; and the extra peg to be used in moving
(define (move-tower size from to extra)
  (cond ((= size 0) #t)
        (else
         (move-tower (- size 1) from extra to)
         (move from to)
         (move-tower (- size 1) extra to from)
         )))

; the primitive move function for the
; towers of hanoi.  This function captures
; moving one disk from peg from to peg to.
; This function has a side effect of printing.
(define (move from to)
  (newline)
  (display "move top disk from ")
  (display from)
  (display " to ")
  (display to))