To clarify, I’m talking about private fields in each object/struct. You could say all functions defined in the same module get access to private struct fields.

To clarify, I’m talking about private fields in each object/struct. You could say all functions defined in the same module get access to private struct fields. That works until you want a more specialized version of some of those functions — essentially, a different module that has access to protected fields. Here’s another example. You’re writing a function `g` that accepts an object of type `Foo` and calls function `f` on it. You have a default implementation of `f`, but you also want to let the caller supply their own implementation. If you have some way of attaching behavior to a type — classes, typeclasses, etc — this is trivial. If not, your function has to explicitly ask for every single function from the caller.