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


Reverse takes any function and returns it with its parameter in the reverse order (in other languages, this function is known as flip). Let's look at the following code:

import arrow.syntax.function.partially3
import arrow.syntax.function.reverse

fun main(args: Array<String>) {
   val strong: (String, String, String) -> String = { body, id, style -> "<strong id=\"$id\" style=\"$style\">$body</strong>" }

   val redStrong: (String, String) -> String = strong.partially3("font: red") //Explicit

   println(redStrong("Red Sonja", "movie1"))

   println(redStrong.reverse()("movie2", "The Hunt for Red October"))


Our redStrong function is awkward to use, as we'll expect to have id first and then body, but, is easily fixable with the reverse extension function. The reverse function can be applied to functions from parameters 1 to 22.