In Functional Programming in Kotlin you will learn
Functional programming techniques for real-world applications
Write combinator libraries
Common structures and idioms in functional design
Simplicity and modularity (and fewer bugs!)
Functional Programming in Kotlin is a reworked version of the bestselling Functional Programming in Scala, with all code samples, instructions, and exercises translated into the powerful Kotlin language. In this authoritative guide, you'll take on the challenge of learning functional programming from first principles. Complex concepts are demonstrated through exercises that you'll love to test yourself against. You'll start writing Kotlin code that's easier to read, easier to reuse, better for concurrency, and less prone to bugs and errors.
About the Technology
Improve performance, increase maintainability, and eliminate bugs! How? By programming the functional way. Kotlin provides strong support for functional programming, taking a pragmatic approach that integrates well with OO codebases. By applying the techniques you'll learn in this book, your code will be safer, less prone to errors, and much easier to read and reuse.
About the Book
Functional Programming in Kotlin teaches you how to design and write Kotlin applications using typed functional programming. Offering clear examples, carefully-presented explanations, and extensive exercises, it moves from basic subjects like types and data structures to advanced topics such as stream processing. This book is based on the bestseller Functional Programming in Scala by Rúnar Bjarnason and Paul Chiusano.
What's Inside
Functional programming techniques for real-world situations
Common structures and idioms in functional design
Simplicity, modularity, and fewer bugs!
About the Reader
For Kotlin developers. No functional programming experience required.
About the Authors
Marco Vermeulen has two decades of programming experience on the JVM.

https://www.oreilly.com/library/view/functional-programming-in/9781617297168AU/