I'm familiar with COM and I do think the kind of interoperability you get with open multiple dispatch is of a different character altogether. There has not been

I'm familiar with COM and I do think the kind of interoperability you get with open multiple dispatch is of a different character altogether. There has not been any theoretical reason why this has to be true yet, but empirically it has been surprisingly powerful in Julia. I guess Common Lispers would relate to it too.