; I know it's not the most efficient of codes but...

; n is the fixed side-length
; m is the current count

; maps out both top and bottom of the square
(define (sides n m pic1)
  (if (= m 1)
      (side n pic1)
      (side n (stack-frac (/ 1 n) (side n pic1) (middles n (- m 1) pic1 blank-bb)))))

; maps out all non-top/bottom lines
(define (middles n m pic1 pic2)
  (if (> m 1)
      (stack-frac (/ 1 m) (middle n pic1 blank-bb) (middles n (- m 1) pic1 pic2))
      (sides n 1 pic1)))

; maps out single line on top/bottom
(define (side n pic1)
  (quarter-turn-left(stackn n (quarter-turn-right pic1))))

; maps out single line on non-top/bottom
(define (middle n pic1 pic2)
  (quarter-turn-left (stack-frac (/ 1 n) (quarter-turn-right pic1) (empty n (- n 1) pic1 pic2))))

; maps out blank space in single non-top/bottom line
(define (empty n m pic1 pic2)
  (if (= m 1)
      (quarter-turn-right pic1)
      (stack-frac (/ 1 m) pic2 (empty n (- m 1) pic1 pic2))))

; from persian input
(define (persian-hole pic n)
  (sides n n pic))

(show (persian-hole (make-cross rcross-bb) 5))