> Nice or not, pretending that double precision floats and arbitrary precision integers can be stacked as a tower is foolish. There are floats that can't be represented as integers, and integers which can't be represented as floats.

The numeric tower in Scheme describes general number types with above of in the tower graphic (in the Wikipedia article) meaning subtype of. double precision floats and arbitrary precision integers are representations of numbers. Both would also be Real numbers.