Folktale

This book is a work in progress!

This is largely a draft at this point, so if you see any problems, feel free to file a ticket and I’ll get to fixing it up asap.

Category Theory is a relatively new branch of mathematics with fairly abstract concepts. Functional programming libraries use such concepts for maximising their abstraction power and general usefulness, but it comes with a certain drawback: most of the constructions provide little or no guidance for concrete use cases. This is a problem in particular with newcomers to this style of programming, who often find themselves lost, asking questions like “But why are Monads useful?”

In this book, you will walk through concrete applications of category theoretical concepts to solving problems, and allow you to build a mental framework to generalising and abstracting problems in a way that makes your code more reusable, and more robust. Do note that this is not a book about Category Theory, but rather we