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 4

  1. Describe a case where an implicit parameter is also an implicit conversion.

This is the case if an implicit parameter is a function: def func[A, T](a: A)(implicit adapter: A => T): T = adapter(a).

  1. Replace the following definition that uses view bounds with one using context bounds: def compare[T <% Comparable[T]](x: T, y: T) = x < y.
type ComparableContext[T] = T => Comparable[T]
def compare[T : ComparableContext](x: T, y: T) = x < y
  1. Why are type classes sometimes said to separate behavior and data?

Because type class instances define logic to work and the data comes from the values the type class is applied to.

It is easy to change the example of possible conflicts in lexical scope so that one of the implicits wins over others and all others can be uncommented without having conflicts anymore. Make this change. For example, it can be done by changing...