We have already come a long way in Scala and in learning about the various design patterns in the language. Now, you should be at a stage where you are confident about when to use specific design patterns and when to avoid them. You saw some of the specifics and nice features of Scala that lead to its expressiveness. We went through the Gang of Four design patterns as well as some important functional programming concepts such as monads. Throughout the book, we have tried to keep mathematics theories to a really basic level, and we have tried to avoid some scary Greek letters in formulas that are hard to understand by non-mathematicians, who may also want to use a functional programming language to its full potential.

The aim of this and the next chapter is to look at Scala from a more practical point of view. Knowing about a language and some design patterns is not always enough for a developer to see the whole picture and...