Who this book is for

If you've ever wrestled with this problem: Undefined is not a function, then this book might be for you. If you're looking for a way to write less defensive code, fewer trivial tests, and not worry about breaking code if you try to refactor, then you may be interested in the concepts of type-driven development.

This book is for you if you are a programmer (it doesn't matter what kind) who's interested in writing safe, efficient code. There are many techniques and processes for achieving that, of course, but type-driven development is one of the most mainstream and accessible.

That being said, this book presents type-driven development using a relatively unfamiliar language. I've tried to write as plainly as possible; but to follow along, you'll still need to learn the rules and logic of a powerful type system. You will reach a point where your mind works in tandem with the compiler, but that will take time and patience. The reward will be that the compiler becomes your friend in writing safer and more correct code.

If you're willing to go on this journey and learn the rules of the type system, then this book is for you.