There were lots of OO Forth implementations back in the day. I used one to make a star field animation system for a planetarium when I was in University. The

There were lots of OO Forth implementations back in the day. I used one to make a star field animation system for a planetarium when I was in University. The main thing I would say, though, is that OO tends to encourage you to put things on the heap. This goes away from one of the nicest aspects of Forth where you are encouraged to play on the stack. I went from Forth to C++ and quickly embraced RAII, partially thanks to my experience with Forth. I've often thought we're missing an abstraction here -- something that helps you with cohesion like OO does, but which doesn't force you away from the really efficient and elegant approach of something like Forth.