Sample Design Process

Source code: racket or text.

This whole page courtesy of Mr. Underriner in 2023.

Problem 1: shape-stack

Recipe Part 1a: a purpose statement

Shape-stack is a function that produces an image of a triangle stacked on top of circle, stacked on top of a square. Shape-stack places each shape inside of shape it is stacked on top of so that everything fits within the square at the base. The function takes in 4 inputs; 3 for the color of each shape, and 1 for the size of the shapes. The function works by using overlay to place the shapes on top of each other, and scale each image to appropriately fit within the image it is stacked on.

Recipe Part 1b: Signature

The signature is:

shape-stack: number(sizing of the shapes) string(triangle color)
             string(circle color) string(squarecolor)
             --> image (shapes stacked)

Instead of number could also have integer or int.

Recipe part 2: examples of function.

Show that you can output the function result for a static example.

(overlay (scale 1.5 (triangle 10 "solid" "red"))
         (overlay (circle 10 "solid" "green")
                  (scale 2 (square 10 "solid" "blue"))))  ;;. result
(overlay (scale 1.5 (triangle 20 "solid" "purple"))
         (overlay (circle 20 "solid" "yellow")
                  (scale 2 (square 20 "solid" "brown"))))  ;; . result

Recipe part 3: Header and Skeleton

Header: you don’t have to do this as a separate comment, just do this before you write the body

(define (shape-stack size colorTri colorCirc colorSqu)
   ...)

Recipe part 4: Inventory

Add an inventory for what you can work with. Textbook places this after the function header - I think that’s ugly.

#|
    size  number 10
    colorTri string "red"
    colorCirc string "blue"
    colorSqu string "green"
|#

Recipe part 5: Function Body

(define (shape-stack size colorTri colorCirc colorSqu)
  (overlay (scale 1.5 (triangle size "solid" colorTri))
           (overlay (circle size "solid" colorCirc)
                    (scale 2 (square size "solid" colorSqu)))))

Recipe part 6: Testing

(check-expect (shape-stack 10 "red" "green" "blue")
              (overlay (scale 1.5 (triangle 10 "solid" "red"))
                       (overlay (circle 10 "solid" "green")
                                (scale 2 (square 10 "solid" "blue")))))
(check-expect (shape-stack 20 "purple" "yellow" "brown")
              (overlay (scale 1.5 (triangle 20 "solid" "purple"))
                       (overlay (circle 20 "solid" "yellow")
                                (scale 2 (square 20 "solid" "brown")))))

Recipe part 7: Solve other problems

Use your program to solve other problems… (we’re not really here yet).

Now that we have shape-stack, we could make a function called collage. Collage puts a bunch of different shape-stacks in a beside/`above display of art. By using shape-stack as part of another function, we can further test it to see if it works. If you don’t test shape-stack before starting collage, and collage does not work as you expect, you will spend more time than necessary debugging.