I simply don't believe that multi method dispatch takes care of it all when it comes to different number systems. While Perl 6 offers a lot of features, to the best of my knowledge The Structure of Computer Programming
is still correct when it says "Developing a useful, general framework for expressing the relations among different types of entities (what philosophers call ``ontology'') seems intractably difficult. The main difference between the confusion that existed ten years ago and the confusion that exists now is that now a variety of inadequate ontological theories have been embodied in a plethora of correspondingly inadequate programming languages. For example, much of the complexity of object-oriented programming languages -- and the subtle and confusing differences among contemporary object-oriented languages -- centers on the treatment of generic operations on interrelated types."
That is not to say that Perl 6 is not an improvement. It is. It just isn't a solution.