February, 2023 Update: Learn Functional Programming Without Fear is one of my best-selling books on Gumroad.com (see the link below).
November, 2022: My new book, Learn Functional Programming Without Fear, is currently an Amazon Java and functional programming #1 new release. The book is now available in three formats:
For OOP developers: Start learning FP the fast way
This is a small book, but it’s a small book with a HUGE goal:
To help object-oriented programming (OOP) developers who use languages like Java, Kotlin, Python, Swift, and C++ learn the concepts that take you to the cusp of using Scala’s two main functional programming libraries: Cats Effect and ZIO.
Furthermore, the book does that in less than 270 pages of text that are written in a simple, conversational style — just like I was pair programming with you, or mentoring you in a small classroom — with plenty of example FP code.
To be clear, when I say “the cusp” of using those FP libraries, when you finish the book, I want you to be able to look at the initial examples in the Cats Effect and ZIO documentation and think:
“I know what they’re doing, and I know why they’re doing it.”
I believe this book is the fastest, simplest way for OOP developers to start learning FP.
Also, as I always do with my books, I offer a large, free preview of the PDF. This version is a little older than the final version of the book, but if you’re unsure, I encourage you to read it before buying it at one of the links above:
As always, I hope you like this new functional programming book, and I hope it’s helpful.
Errata (bugs/issues in the book)
In the place where I use this in the book:
type Money = Double
I should have used something like this instead:
type Money = BigDecimal // do this type Money = Long // OR this
Bonus: Functional Programming resources
As an ongoing resource for anyone who has read this book, here are some of the best FP resources I know:
- My much larger FP book, Functional Programming, Simplified
- Video: Real-world functional programming in Scala using ZIO, by Yonas Ghidei
- The ZIO website
- The Cats Effect website
More-complicated functional programming resources
- Bartosz Milewski’s PDF, The Dao of FP is rich in category theory
All the best,