We describe arithmetic algorithms on a canonical number representation based on the Catalan family of combinatorial objects specified as a Haskell type class. Our algorithms work on a {\em generic} representation that we illustrate on instances members of the Catalan family, like ordered binary and multiway trees. We validate the correctness of our algorithms by defining an instance of the same type class based the usual bitstring-based natural numbers. While their average and worst case complexity is within constant factors of their traditional counterparts, our algorithms provide super-exponential gains for numbers corresponding to Catalan objects of low representation size.