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 12

  1. What is the meaning of the Behavior[Tpe] definition?

Behavior[Tpe] explicitly specifies that this actor is capable of handling messages that are subtypes of Tpe. By recursion, we can conclude that the returned behavior also will be Behavior[Tpe].

  1. How do you get access to the scheduler in the actor's behavior?

The schedule is accessible via the behavior constructor, Behaviors.withTimers.

  1. Describe possible ways an actor can be stopped.

An actor can be stopped by the parent using the parent's actor context: context.stop(child).

An actor can also stop itself by returning respective behavior: Behaviors.stopped.

An actor can also be stopped if an exception was thrown by the actor's logic and the SupervisorStrategy defined for this actor is stop.

  1. What is the difference between a local and a cluster receptionist?

There are different implementations but...