Nested Pinwheels Code

# A Pinwheel is an angle of rotation
data Pinwheel:
  | pw(angle :: Number)
end

# A PinwheelState is 4 Pinwheels
data PinwheelState:
  | pinwheels(
      p1 :: Pinwheel,
      p2 :: Pinwheel,
      p3 :: Pinwheel,
      p4 :: Pinwheel)
end

STARTING-PINWHEELS = pinwheels(pw(60), pw(3), pw(25), pw(70))

# update-pinwheel :: Pinwheel -> Pinwheel
fun update-pinwheel(p):
  pw(p.angle + 6)
end

# next-state-tick :: PinwheelState -> PinwheelState
fun next-state-tick(ps):
  pinwheels(
    update-pinwheel(ps.p1),
    update-pinwheel(ps.p2),
    update-pinwheel(ps.p3),
    update-pinwheel(ps.p4))
end

# draw-pinwheel :: Pinwheel -> Image
fun draw-pinwheel(p):
  rotate(p.angle, PINWHEEL-IMG)
end

# draw-state :: PinwheelState -> Image
fun draw-state(ps):
  put-image(draw-pinwheel(ps.p1),
    400, 100,
    put-image(draw-pinwheel(ps.p2),
      320, 240,
      put-image(draw-pinwheel(ps.p3),
        100, 400,
        put-image(draw-pinwheel(ps.p4),
          500, 350,
          empty-scene(640, 480)))))
end