Adaptation of std::ratio for Hana.
Comparablestd::ratios are compared for equality using std::ratio_equal. Orderablestd::ratios are ordered using std::ratio_less. Monoid, Group, Ring, and EuclideanRingstd::ratios are added, subtracted, multiplied and divided using std::ratio_add, std::ratio_subtract, std::ratio_multiply and std::ratio_divide, respectively. Furthermore, the neutral element for the additive operation is std::ratio<0, 1>{}, and the neutral element for the multiplicative operation is std::ratio<1, 1>{}.