* Documentation
* Clean up code
* Ensure equality and order operations are simplified properly
* Check why it is not possible to derive the mixin directly in the instance
E.g. this does not work:
HB.instance Definition _ := [derive eqMixin for foo].
* Find a better way of writing packing functions (cf. infer.v and the derive notation in eqtype.v)
* By default, [derive nored eqMixin for ...] does not simplify the type of the mixin
