Book Image

Functional Kotlin

By : Mario Arias, Rivu Chakraborty
Book Image

Functional Kotlin

By: Mario Arias, Rivu Chakraborty

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

Infix functions

Functions (normal or extension) with just one parameter can be marked as infix and used with the infix notation. The infix notation is useful to express the code naturally for some domains, for example, math and algebra operations.

Let's add an infix extension function to the Int type, superOperation (which is just a regular sum with a fancy name):

infix fun Int.superOperation(i: Int) = this + i

fun main(args: Array<String>) {
   1 superOperation 2

We can use the superOperation function with the infix notation or normal notation.

Another area where the infix notation is commonly used, is on assertion libraries, such as HamKrest ( or Kluent ( Writing specification code in a natural, easy to understand language is a huge advantage.

Kluent assertions look like natural English expressions:

"Kotlin" shouldStartWith "Ko"

Kluent also comes with a backtick version for even greater...