What are the fundamentals of OO? Those principles of immutability and referential transparency seem to require writing pretty unidiomatic code when working with OO languages.
Rather than saying the fundamentals are more similar than given credit for, perhaps I should say the fundamentals overlap more than given credit for.
I'm having a hard time finding a concrete example at the moment, but I've seen fragments in Java codebases that, if you squint a little, seem almost functional. Of course, the code was very, very ugly, but semantically was quite functional.
I'm not trying to defend OOP. My view is that the benefits of FP outweigh the benefits of OOP. If we could find a way to import the benefits of each into the other, we'd have the best of both worlds. (Of course, then everyone would find something new to argue about ;) ).
