Kotlin is quite powerful, and data classes are proving just that. You have learned how the language and the compiler work together to provide you with boilerplate-free constructs. We get to extend our keyboard's lifetime while focusing more on the problem to be solved. You have also seen how destructing an object in a number of variables can prove to be quite handy and promotes code that is a lot more readable.
In Chapter 10, Collections, we will cover the Kotlin extensions to the Java collections library. This chapter introduces the mutable versus immutable state, and why the latter can be useful. It also shows the Kotlin additions, which make using collections easier than Java.