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

Basics concepts

Functional programming is composed of a few well-defined concepts. A short introduction of these concepts will follow and, later on, each concept will be covered in depth, in the next chapters.

First-class and higher-order functions

The most foundational concept of functional programming is first-class functions. A programming language with support for first-class functions will treat functions as any other type; such languages will allow you to use functions as variables, parameters, returns, generalization types, and so on. Speaking of parameters and returns, a function that uses or returns other functions is a higher-order function.

Kotlin has support for both concepts.

Let's try a simple function (in Kotlin's documentation this kind of function is named lambda):

val capitalize = { str: String -> str.capitalize() }

fun main(args: Array<String>) {
   println(capitalize("hello world!"))

The capitalize lambda function is of type (String) -> String; in other words...