Book Image

Functional Kotlin

Book Image

Functional Kotlin

Overview of this book

Functional programming makes your application faster, improves performance, and increases your productivity. Kotlin supports many of the popular and advanced functional features of functional languages. This book will cover the A-Z of functional programming in Kotlin. This book bridges the language gap for Kotlin developers by showing you how to create and consume functional constructs in Kotlin. We also bridge the domain gap by showing how functional constructs can be applied in business scenarios. We’ll take you through lambdas, pattern matching, immutability, and help you develop a deep understanding of the concepts and practices of functional programming. If you want learn to address problems using Recursion, Koltin has support for it as well. You’ll also learn how to use the funKtionale library to perform currying and lazy programming and more. Finally, you’ll learn functional design patterns and techniques that will make you a better programmer.By the end of the book, you will be more confident in your functional programming skills and will be able to apply them while programming in Kotlin.
Table of Contents (22 chapters)
Title Page
Copyright and Credits
Packt Upsell

Extension functions

Definitively, one of the best features of Kotlin is extension functions. Extension functions let you modify existing types with new functions:

fun String.sendToConsole() = println(this)

fun main(args: Array<String>) {
   "Hello world! (from an extension function)".sendToConsole()

To add an extension function to an existing type, you must write the function's name next to the type's name, joined by a dot (.).

In our example, we add an extension function (sendToConsole()) to the String type. Inside the function's body, this refers the instance of String type (in this extension function, string is the receiver type).

Apart from the dot (.) and this, extension functions have the same syntax rules and features as a normal function. Indeed, behind the scenes, an extension function is a normal function whose first parameter is a value of the receiver type. So, our sendToConsole() extension function is equivalent to the next code:

fun sendToConsole(string: String) = println...