Catagory theory is a fantastic tool for understanding programming language design. As a user, you don't need to understand catagory theory, but you benifit when

Catagory theory is a fantastic tool for understanding programming language design. As a user, you don't need to understand catagory theory, but you benifit when the language designers do. As a software engineer, category theory is sometimes useful in API design as well; although more often than not, your API is constrained by the existing ecosystem too much for category theory to give you much benefit (and, frankly, simple enough that category theory is overkill).