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)

Polymorphism and higher order functions

Until now, we've played with functions that operate on only one type of data (monomorphic functions). Now, we will finally apply our type system knowledge to build functions that work for multiple types. Functions that take type parameters are called polymorphic functions similar to polymorphic methods implemented in an object-oriented hierarchy of classes (subtype polymorphism). For functions in Scala, it is called parametric polymorphism.

Polymorphic functions

We have already used polymorphic functions when we played with Glass examples in the previous chapter:

sealed trait Glass[+Contents]
case class Full[Contents](c: Contents) extends Glass[Contents]
case object EmptyGlass...