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 6

  1. What would be the proper effect to represent getting each of the following:
  • The first element of some List: Option[?] with None representing an empty list does not have a head element
  • A list of tweets: Future[List[Tweet]] as the operation will probably take some time as it goes over the network
  • User information from the database for a given userId: Future[Option[?]] with Future denoting the network call and Option denoting no user account for a given userId
  1. What is a range of possible values of the following expression: Option(scala.util.Random.nextInt(10)).fold(9)(_-1)

An inclusive [-1;9]

  1. What will be the result of the following expression:
Try[Int](throw new OutOfMemoryError()).filter(_ > 10).recover {
case _: OutOfMemoryError => 100

The Try constructor will not catch an OutOfMemoryError, hence the given expression will throw the OutOfMemoryError...