I love Ruby with all my heart but that seems to be quite a mess. While a not-well-thought-through feature in some application can be forgiven (and maybe even removed), in language design it cetainly has no place. And while this should be a secondary consideration, I really feel for those poor JRuby and Rubinus guys. As if Ruby wasnt "dynamic" enough, the sheer complexity of implementing refinements must be awful!

I think, they should just leave it out (at least for now) and rather spend some more time on performance, stabilty and memory usage in MRI...