> Let's reify. If I were to create a bunch of matrix classes (matrix-float, matrix-double, ignoring the lack of sugar), CL provides no way to declare a generic method 'mref' to be intelligent enough to know what the output will be, given the input type.

I am not sure if I follow you.

If you have "matrix-float, matrix-double" you are perfectly able to define a "mref" generic method that acts smartly depending on the input type. This is one of the most basic features of the CLOS OOP system. Maybe there is something missing on your explanation?