Yes, standard library. I understood the poster above you to suggest they shouldn't be a part of language by that's used by default, for sure though it would be convenient to have centralized implementation.
Exactly. Having a rational datatype as easily usable as float would make it easier to use as a default when you don't really need floats but just non integers. Which is often the case if you think about it. Automatic simplifications, literals (12.345122 is a rational, as well as 22/7)