I think this quote (from the first chapter of the "book") sums it up nicely: > Category theory is extreme in the sense that it actively discourages us from loo

I think this quote (from the first chapter of the "book") sums it up nicely: > Category theory is extreme in the sense that it actively discourages us from looking inside the objects. An object in category theory is an abstract nebulous entity. All you can ever know about it is how it relates to other object — how it connects with them using arrows. I think it's a great way to learn a different approach to solving math problems and, more importantly, computer science problems. When you start to think of objects not as what they are but what they can be, you get an extremely natural inclination towards immutability and, assuming your chosen language has a powerful type system, an awesome "free" mitigation against programming errors. With category theory, you easily formulate your thoughts into function composition, and can more readily rely on the type system to validate your code. This is pretty much what you must do in Haskell, but it's useful in imperative languages as well. There's a reason functional paradigms are leaking into Java, C++, Python, etc: they're mighty useful.