The OCaml object system is still parametric polymorphism (trying to pass itself as subtyping polymorphism through row variables) rather than ad-hoc polymorphism: there are still no functions that only work on a finite subset of types. In other words, a function may work on any objects that has a method `m`, but you cannot have the same method that has different implementation for `int` and `float`.

It uses structural typing not ad-hoc polymorphism. Plus it’s rarely used and it used to give hard to parse error messages when you made type mistakes. I don’t really see it as an adequate replacement for ad-hoc polymorphism.