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 2

  1. Which type constraints can you name?

There are two constraints: the lower bound or subtype relation and the upper bound or supertype relation.

  1. What implicit type constraints are added to a type if there are no type constraints defined on it by the developer?

For missing upper bound, the compiler adds Any as a constraint, and, for missing lower bound–Nothing.

  1. Which operators can be used to refer to the nested type of some type?

There are two operators. The notion A#B refers to the nested type of the A type. The notion of a.B refers to the B subtype of the instance a.

  1. Which type can be used as an infix type?

Any type which is parameterized by exactly two type parameters.

  1. Why is the use of structural types discouraged in Scala?

Use of structural types often leads to generated byte code, which accesses methods via reflection, which is slower than normal...