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)


Scala 2.13 is a minor update of Scala with the main focus on the redesigned collection library. The few small additions to the standard library, such as automatic resource management, just accentuate this fact.

The new collection library mainly consists of two intermixed inheritance hierarchies with a similar shape. Members of the first hierarchy describe the structure of the collection and members of the second hierarchy—operations available on this collection type. Because of the inheritance relations, the collections situated lower in the tree define additional methods for more specific collections and override methods defined by the parent traits to provide more efficient implementation as required.

The three main collection types are Seq, Set, and Map. Each of these types has multiple implementations that are useful in specific situations. Set is also a function of one argument; Seq and Map are PartialFunctions.

Most of the collections are available in mutable and immutable forms.

In addition to the collection hierarchies, there is a concept of View, which is a reified definition of iterators’ operations and can be used to lazily apply transformations to the collection. Another related abstraction is IterableFactory, which implements some general ways to create collection instances and to perform conversions between collection representations.

In the next chapter, we will shift our focus from the new features of version 2.13 to a general exploration of Scala, starting with its type system.