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)

Implicit scope resolution

In order to put the implicits in the places where they are required, the compiler first has to find them. This process is called implicit scope resolution and has well-defined rules in order to guarantee that implicits are determined as expected by the language specification and the developer using them. Implicit scope resolution is a three-step process.

Or four-step, if we count the case where the implicit parameter is provided explicitly as an argument to the method. We'll consider this case as number zero and won't take it into the account because it has the highest precedence and does not involve implicit lookup.

We'll provide a short overview of these steps so that we have them in one place for easy reference and then go into the details of each on the list:

  • The current invocation (or lexical) scope. It has precedence over the implicit...