I think this is pretty insightful. It's easy to hate on OO because of something along the lines of it not being a neat mathematical formalism, which can facile

I think this is pretty insightful. It's easy to hate on OO because of something along the lines of it not being a neat mathematical formalism, which can facilely be argued as strictly a deficiency: if you don't look too closely, it certainly appears as only a deficiency. I think a deeper look inevitably runs into two things: (1) certain domains are more easily approached through spare mathematical formalisms than others. E.g. if the domain you're modeling is already most easily thought about in terms of compositions of mathematical transformations, you should probably model it functionally. (2) Finding a declarative characterization of the results you'd like, or a neat chain of functional compositions which produce it, typically takes more work up front. (For many projects, the initial work up front is worth it—but for lots and lots of others, it's essentially over engineering.) OO is often not 'ideal,' but frequently, solidly pragmatic. As a paradigm, the aesthetic behind it reminds me of TypeScript's designers intentionally foregoing soundness of the type system.