Let’s make an animation.

Define some variables as follows.

val sizeOfLamp = 250
val redLamp    = circle(sizeOfLamp, Red)
val yellowLamp = circle(sizeOfLamp, Yellow)
val greenLamp  = circle(sizeOfLamp, Green)
val trafficLights = Buffer(redLamp, yellowLamp, greenLamp)

Package o1 provides an effectful function animate that displays a number of images one after another, thus turning them into an animation. The function expects two parameters:

• a bufferful of pictures; and

• a positive number (Double), that determines the speed of the animation. A larger number results in a faster animation.

Experiment with animate. In the field below, enter a command that animates the contents of the buffer that the variable trafficLights. Use the speed 1.0. If you want, go ahead and come up with other things to animate.