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)

Monad transformers

Let's hold on for a second and recap what we just did.

We made a small sacrifice and increased the complexity of the return type of our original functions to some "common denominator" type. This sacrifice is rather small because in our example, as well as in real life, this is usually done by just lifting the original functions into their proper context.

The signatures we came up with look a little awkward, but this is partly because we started to develop them as concrete implementations. In fact, the user-facing API of our fishing component should be similar to the following snippet straight from the beginning, if implemented in a more abstract way:

abstract class FishingApi[F[_]: Monad] {

val buyBait: String => F[Bait]
val castLine: Bait => F[Line]
val hookFish: Line => F[Fish]

def goFishing(bestBaitForFish: F[String]): F[Fish]...