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 7

  1. Why is the property of associativity essential for the monoid to be useful in a distributed setup?

In a distributed setup, we're usually talking about folding and reusing datasets with parts of the data being processed by different computers. Monoidal operations are applied on remote machines. Regardless of the order in which they were sent from the master machine, network delays, different load patterns, and hardware settings will influence the order in which they will be returned. It is important to be able to apply an operation on the intermediate results already at hand without waiting for the first operations to complete.

  1. Implement a monoid for Boolean under OR.

The implementation is as follows:

implicit val booleanOr: Monoid[Boolean] = new Monoid[Boolean] {
override def identity: Boolean = false
override def op(l: Boolean, r: Boolean): Boolean = l |...