With fairness, no you can't, not truly. Please point me to the version of HM the works with inheritance. Plus, due to stuff like __getattr__, the interpreter may not know until the method is called if it even exists.
It would be totally possible in python to write a class where when any arbitrary method is called on a class, a function is randomly generated and called, with a random number of arguments, etc. It doesn't even have to be consistent from call to call. How on earth would H-M type inference cope with that?
The point is you can't just bolt on H-M to a typical scripting language and expect it to work, like, at all. It's a pretty huge sea change, and it would warp the underlying language to the point where you'd just end up with some of non-lazy, non-pure Haskell.
It would be totally possible in python to write a class where when any arbitrary method is called on a class, a function is randomly generated and called, with a random number of arguments, etc. It doesn't even have to be consistent from call to call. How on earth would H-M type inference cope with that?