[jhc] How to add Num instance to Foreign.C.Types.CLong?

[David Roundy]

Hello,

I'm wondering how one would go about adding a Num instance to CLong?
So far as I can see in

lib/jhc/Foreign/C/Types.hs

it's a completely opaque data type, so I've no idea how to go about
adding instances.  Of course, most of these type would benefit from
being members of a whole slew of classes, but I can't see how to go
about doing this.  Any hints?
-- 
David Roundy