Book Image

Professional Scala

By : Mads Hartmann, Ruslan Shevchenko
Book Image

Professional Scala

By: Mads Hartmann, Ruslan Shevchenko

Overview of this book

This book teaches you how to build and contribute to Scala programs, recognizing common patterns and techniques used with the language. You’ll learn how to write concise, functional code with Scala. After an introduction to core concepts, syntax, and writing example applications with scalac, you’ll learn about the Scala Collections API and how the language handles type safety via static types out-of-the-box. You’ll then learn about advanced functional programming patterns, and how you can write your own Domain Specific Languages (DSLs). By the end of the book, you’ll be equipped with the skills you need to successfully build smart, efficient applications in Scala that can be compiled to the JVM.
Table of Contents (12 chapters)

Exploring Pattern Matching

Now we will return to pattern matching and learn about extending capabilities behind case classes. As you will remember from the previous chapter, we can use pattern matching against case classes, where fields of a class can be bound to the variables in the scope of an appropriative case clause. Can we do this for our non-case classes and embed our own custom logic for matching?

In this section, we will learn how to write our own pattern matcher and get acquainted with some standard generic classes which are often used with pattern matching.

Now, let's get started with the minimal example.

  1. First, we write the following code in the IDE:

    case class Wrapper(x:Int)
    w match {case Wrapper(x) => doSomething(x)}
  2. Under the hood, the compiler compiled this to the next intermediate form:

    val container = Wrapper.unapply(w)
    if (container.isDefined) {
    	val x = container.get
    • The unapply method of the companion object is called, which must return the class...