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)


Option is probably the first effect that a novice Scala developer gets familiar with. It encodes the situation that the function might return no result. Simplified, it is represented in stdlib as an algebraic data type, as shown in the following code:

sealed abstract class Option[+A]
case object None extends Option[Nothing]
final case class Some[+A](value: A) extends Option[A]

None represents the case of an absent result, while Some(value) represents the case where a result exists. Next, we'll look at a three-step approach to gain more understanding of how to work with an Option—how to create it, read the value from it (if there is one) and which possibilities emerge from the fact that Option is an effect.

Creating an Option