Scala is a functional programming language and, as such, it supports design patterns based on concepts such as monoids, monads, and others. We already saw these in Chapter 10, Functional Design Patterns - the Deep Theory, and we know the rules they follow and the structure they have. We wrote everything ourselves, but a library already exists that does this for us—Scalaz (https://github.com/scalaz/scalaz). This library is used when we need purely functional data structures.
Another library that has a similar popularity to Scalaz in the community is Cats (https://github.com/typelevel/cats). They should both be able to help developers achieve the same functional programming concepts. In most cases, the choice between the ...
