Functional Kotlin

Introduction

The book Functional Kotlin (authors Mario Arias and Rivu Chakraborty, 2018, 350 pages) is a practical guide to applying the functional approach in the Kotlin language. Although Kotlin natively supports both object-oriented and functional programming, many developers use only a small part of its capabilities. This book aims to fill that gap and show how to write cleaner, more predictable, and easily testable code.

What the book is about

The authors progressively introduce the reader to key concepts of functional programming (FP) and demonstrate their implementation in Kotlin. The book covers:

• FP basics: pure functions, immutability, absence of side effects.
• Working with higher-order functions, lambda expressions, and anonymous functions.
• Function composition and currying.
• Functors, applicative functors, and monads — from theory to practical examples.
• Working with collections in a functional style (map, filter, fold, flatMap).
• Error handling without exceptions (Option, Either, Try).
• Concurrency and asynchrony using functional approaches.
• Testing functional code.

Who this book is for

The book is intended for developers already familiar with the basics of Kotlin (syntax, classes, basic constructs) but wishing to delve deeper into the functional paradigm. It will be useful