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)

Chapter 11

  1. Name two ways in which an actor can change itself in response to the received message.

An actor can mutate its internal state using a var field. This is a classical object-oriented approach.

Another way is to use context and become close over some value which will become part of the new state. The context.become can also be used to change the behavior of the actor completely. This is a more functional approach because both state and behavior are in fact immutable.

  1. What is the purpose of ActorRef?

The ActorRef provides a means to address an actor via the actor path. It also encapsulates an actor's mailbox and a dispatcher. Actors in Akka communicate via ActorReference.

  1. Look up in the official documentation the description of the system guardian. What is the main purpose of it?

The main purpose of the system guardian is to supervise system level actors. It...