Adapt the function move-picture from exercise 10.3.6 to use the structure-mutating functions from exercise 41.4.1.
Turn the functions translate-circle and translate-rectangle of exercises 6.6.2 and 6.6.8, respectively, into structure-mutating functions. Adapt move-circle from section 6.6 and move-rectangle from exercise 6.6.12 so that they use these new functions.
Exercises 6.6.2
Use fun1or-circle to develop draw-a-circle. The function consumes a circle structure and draws the corresponding circle on the screen. Use (start 300 300) to create the canvas before testing the function.
Exercise 6.6.12
Here is the move-rectangle function:
It draws and clears a rectangle circle on the canvas and then produces a translated version.
Develop draw-and-clear-rectangle, which draws a rectangle, sleeps for a while, and then clears the rectangle. Finally, create a rectangle and use the functions of this exercise set to move it four times.