;; The first three lines of this file were inserted by DrScheme. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-intermediate-lambda-reader.ss" "lang")((modname red_pattern) (read-case-sensitive #t) (teachpacks ((lib "master.ss" "teachpack" "htdp") (lib "draw.ss" "teachpack" "htdp") (lib "gui.ss" "teachpack" "htdp"))) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ((lib "master.ss" "teachpack" "htdp") (lib "draw.ss" "teachpack" "htdp") (lib "gui.ss" "teachpack" "htdp")))))
(define-struct mypair (left right))

;; Write a function that, given a list of mypairs of numbers, creates a list of 
;; sums of left and right

(define lop (list (make-mypair 2 3) (make-mypair 5 6) (make-mypair 3 7)))

(define (sum-pair lop)
  (cond
    [(empty? lop) empty]
    [else (cons (+ (mypair-left (first lop)) 
                   (mypair-right (first lop))) 
                (sum-pair (rest lop)))]
  )
)

(sum-pair lop)
;; expected
(list 5 11 10)

(define (number-elements nlol)
  (cond
   [(empty? nlol) 0]
   [(number? (first nlol)) (+ 1 (number-elements (rest nlol)))]
   [else (+ (number-elements (first nlol))
            (number-elements (rest nlol)))]
  )
)

(number-elements (list 1 2 (list 4 5) (list 3 (list 6))))
;; expected value
6

(start 400 400)

(define (draw-square x y side min-side color)
  (cond
    [(< side min-side) true]
    [else (and
           (draw-solid-rect (make-posn x y) (/ side 2) (/ side 2) color)
           (draw-solid-rect (make-posn (+ x (/ side 2)) (+ y (/ side 2))) (/ side 2) (/ side 2) color)
           (draw-square x (+ y (/ side 2)) (/ side 2) min-side color)
           (draw-square (+ x (/ side 2)) y (/ side 2) min-side color))]
  )
)

(draw-square 0 0 256 20 'red)