Actually, R5RS says: An operation may, however, return an exact result if it can prove that the value of the result is unaffected by the inexactness of its arguments. For example, multiplication of any number by an exact zero may produce an exact zero result, even if the other argument is inexact. In some environments this sort of thing can be a fast path. This actually is exactly what some people really do not like about R5RS. Personally, the fact that both Stalin and mzscheme actually exist suggests a curious sort of happiness... Regards, Rohan This reminds me of pop music, "I'm no fucking Buddhist, but this is enlightenment"... :?