[wwright]

I can’t speak for all functional programming advocates, but personally, when I criticize “classes” it is because of the overall design/culture and not because of encapsulating state/side effects.

- Subclassing is notoriously misleading and confusing and almost never truly useful (true subclassing, not abstract subclassing/interfaces).

- Class syntax/semantics are usually divorced from the other semantics of the language; closures are usually a much simpler design to achieve the same power. (You can get class-like ideas with simpler ideas too, but I think most “class” features don’t.)

- Culturally, classes are often viewed as mythic/special in a way that’s kind of out of touch with mapping problems to solutions. Look at “typical” Java code full of classes for crazy tasks like implementing 20 getters and constructing a factory to create callbacks. All of these things are related to the problem, but there’s a lot of friction/mismatch because people are taught to “use classes.”