Functional Programming in Kotlin

Introduction

The book «Functional Programming in Kotlin» (authors: Marco Vermeulen, Rúnar Bjarnason, Paul Chiusano, 2021, 360 pp.) is an adaptation of the famous bestseller «Functional Programming in Scala» for the Kotlin language. It offers a deep dive into the functional programming (FP) paradigm using modern Kotlin features. Although the site is dedicated to Python, this book will be useful for anyone who wants to master FP on a strictly typed JVM language and transfer the acquired knowledge to other languages, including Python.

What the book is about

The book starts with the basics: pure functions, immutability, referential transparency. It then sequentially introduces key FP concepts: higher-order functions, currying, composition. The main part focuses on working with data types: Option, Either, List, Stream and building functional libraries based on them. The authors thoroughly discuss monads, functors, applicative functors, and monad transformers. Special attention is paid to testing, parallelism, and working with state in a pure functional style.

Who this book is for

• Kotlin developers who want to learn functional programming from scratch.
• Java or other JVM language programmers transitioning to Kotlin and interested in FP.
• Specialists familiar with FP in Scala or Haskell but wanting to see an implementation in Kotlin.
• Anyone who wants to write more reliable, testable