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)


Either represents the possibility of a function having one of two alternative results which can't be represented by a single type.

For example, let's imagine that we have a new simulation system that replaced an old one. The new system is very popular, and so is constantly under load and thus not always available. The old one is kept as a fallback for this reason. Unfortunately, the results of the simulation have very different formats for both systems. Hence, it makes sense to represent them as Either:

type OldFormat
type NewFormat

def runSimulation(): Either[OldFormat, NewFormat]

If this example gives you the feeling that types of alternatives must be related, then you are getting the wrong feeling. Usually, the types of the results would be completely unrelated. To illustrate this, let's consider another example.

As we're fishing, there is the possibility...