access numeric data in module

I'm the maintainer of the PL/Haskell language extension. (
https://github.com/ed-o-saurus/PLHaskell/)

I want to be able to have a function received and/or return numeric data.
However, I'm having trouble getting data from Datums and building Datums to
return. numeric.h does not contain the macros to do this. They are in
numeric.c.

Is there a way to access the values in the numeric structures? If not,
would a PR to move macros to numeric.h be welcome in the next commitfest?

-Ed