Hi, I am looking for a template library that can handle compile time rationals, ideally with a similar interface to mpl::int_ and that plays well with boost::rational (the dynamic type). First I found boost/mpl/math/rational_c.hpp but soon I realized that it doesn't work with basic operations like mpl::plus, it doesn't even simplify reducible fractions (i.e. 2/4 -> 1/2), in fact it looks like it is just the storage of two (static) integers. Is this something that will be developed in the future or am I using it in the wrong way? Then I found boost::units::static_rational which is more promising, because it simplifies fractions and works with mpl::plus, but it is not integrated with boost::rational nor has an interface similar to that of mpl metatypes. Is there a way of extending mpl::math::rational_c with the existing libraries in boost, or a simple way to make boost::units::static_rational have an interface similar to mpl and also have a value type that returns it runtime boost::rational value? Thank you, Alfredo