Mostly Adequate Guide to Functional Programming
Been reading this book by Professor Frisby on the Kindle lately. I can only assume that’s a pseudonym ol’ Frisby boy.
It’s free, open source (written in Markdown) and all in Javascript, though the concept of FP can of course be used in many many languages. The book’s repository also has some small exercises to complete after some of the chapters, with Mocha tests to ensure you understand what you’ve read and are able to put it into practice. I cloned the project repo myself and have began running through them.
Oh and it has a touch of light humour too, which many programming books are missing in my opinion.
Check it out here: Mostly Adequate Guide.