Book Image

Learn Scala Programming

By : Slava Schmidt
Book Image

Learn Scala Programming

By: Slava Schmidt

Overview of this book

The second version of Scala has undergone multiple changes to support features and library implementations. Scala 2.13, with its main focus on modularizing the standard library and simplifying collections, brings with it a host of updates. Learn Scala Programming addresses both technical and architectural changes to the redesigned standard library and collections, along with covering in-depth type systems and first-level support for functions. You will discover how to leverage implicits as a primary mechanism for building type classes and look at different ways to test Scala code. You will also learn about abstract building blocks used in functional programming, giving you sufficient understanding to pick and use any existing functional programming library out there. In the concluding chapters, you will explore reactive programming by covering the Akka framework and reactive streams. By the end of this book, you will have built microservices and learned to implement them with the Scala and Lagom framework.
Table of Contents (19 chapters)


With functor, we now have a convenient way to apply functions to the contents of an effect, regardless of the type of the effect itself. We were able to check the fish and cook it by applying the same logic we had for an effect-free fish. To get even more comfortable with functors, we will now make a fish pie with our new tool.

First, we'll define a function to make a pie from a single fish:

final case class FishPie(weight: Int)
import ch08.Model._
def bakePie(fish: FreshFish, potatoes: Int, milk: Float): FishPie = FishPie(

That was easy—one fish, one pie, with the size of the fish. Now, we are ready to bake every fish in the bucket:


Oops! This won't compile because the functor only accepts the function of one argument, and we have three.

What can we do? One of the possibilities would be to...