Some comments from from a discussion last month about the book Category Theory for Programmers by Bartosz Milewski:

• "... Peter Freyd once said that the purpose of category theory was to prove that that which is trivial is trivial for trivial reasons. It certainly helped me as a mathematician, because it tells you what's actually hard and what is merely complicated. ..." - smaug123
• "I'd describe category theory as the study of connected things. It turns out that many things are connected, and often the connections are exactly what makes something both interesting and complicated. Getting better at those sorts of problems is a concretely useful skill. ..." - imh
• "My impression so far is that CT teaches you a set of orthogonal abstractions (call them patterns if you like) that will allow you to talk about ideas very precisely. To some degree, being able to talk about ideas makes it easier to have new ones. ..." - kaeluka
• "Category theory is more of a way of thinking rather than a bag of techniques to brute your way through specific problems. Thinking in this way can sometimes bring more clarity. ..." - laxd

(cf. Greatest Inventions (2011-06-09), Cakes, Custard, and Category Theory (2016-02-14), Category Theory Concepts (2016-04-25), Bird's-Eye View (2016-07-20), ...) - ^z - 2017-05-12