[stack] Cat Type Inference

I've written a short article explaining how to infer the types using
the example of a non-trivial higher order function: "[] eval eval" at
http://cdiggins.com/2007/04/11/type-inference-example-in-cat/ for
those interested in a more down to earth explanation of the type
inference algorithm.

Cheers,
Christopher Diggins
http://www.cdiggins.com