✏️ 4.1.2.2 Whiteboard Practice: Composition

You will get a chance to practice whiteboarding a lot during this course section. Time will be set aside during most class sessions at the discretion of your teacher. Use this time wisely to improve both your whiteboarding and functional programming skills!

Practice with Composition

Practice these problems with your pair/instructors.

Problem #1

Compose a function called paint() and then add it to three different painters. Each painter can only paint with one color. This should be the end result:

> painter1.paints()
"Paints green!"
> painter2.paints()
"Paints yellow!"
> painter3.paints()
"Paints red!"

Problem #2

Compose a function called sound(). You should be able to add the following functionality to the objects listed:

> faucet.sound()
"Drip drip drip."
> oldCar.sound()
"Grumble grumble"
> sleepyBear.sound()
"Grrr...yawn"

Problem #3

Compose a function called toss(). The toss() function should determine the distance and speed a battle robot can toss a spear. This function should be unary, so you will need to use currying.

Next, add the toss() function to multiple battle robots. A result might look something like this:

> battleRobot1.toss();
"The battle robot tosses the spear 100 yards at 200 miles per hour!"

Problem #4

First use closures to create three dance moves. For instance, a dancer should be able to do the following:

> dancer.samba()
"The dancer sambas!"
> dancer.tango()
"The dancer tangos!"

Then add the dance moves to a dancer.