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

Function composition

One big part of functional programming as a concept is to use functions in the same way that we use any other type—as values, parameters, returns, and so on. One thing that we can do with other types is to take them as construction blocks to build other types; the same concept can be applied to functions.

Function composition is a technique to build functions using existing functions; similar to Unix pipes or channel pipelines, the result value of a function is used as a parameter for the next one.

In Arrow, function composition comes as a set of the infix extension functions:




Takes the result of invoking the right-hand function as the parameter for the left-hand function.


Takes the result of invoking the left-hand function as the parameter for the right-hand function.


Is an alias for forwardCompose.


Let's compose some functions:

import arrow.syntax.function.andThen
import arrow.syntax.function.compose
import arrow.syntax.function...