No disagreements here. But two quick comments: (1) There is still a software-design aspect to all this that has been neglected. For example, one can find all k

No disagreements here. But two quick comments: (1) There is still a software-design aspect to all this that has been neglected. For example, one can find all kinds of material on how to design OO software (e.g., the GoF book and its offspring). Find me something about how to design software using composable components. There isn't much out there. (2) "Software engineers need category theory" is a statement that is almost too vague to be discussed. Certainly, a traditional presentation of category theory is largely useless to these people. What exactly is useful, and how should it be presented? People are starting to answer these questions, but only starting. Note, for example, that, in the brief intro to categories in the linked article, the fact that the categories allow for multiple identities (one for each object) is glossed over. It this a good idea? I don't know.