Patrick LeBoutillier wrote:
BTW: Does what I'm trying to do make any sense at all? Does anyone know of a better/simpler way to do this (i.e making most of these computations independant of the exact underlying type)?
Actually, I would try to mostly avoid typeclasses. If you want to change the representation sometime, that's still possible if you have abstraction! maybe like data IPAddr n = IPAddr n n where typically n would be Word32 or Word128(does that exist?), and a polymorphic function doing math on it might use a (Num n) => context. Actually you might sometimes need to know what kind of address it is. Then I guess we could have data IPVersion = V4 | V6 class IPAddrRepr n where ipVersion :: n -> IPVersion instance IPAddrRepr Word32 where ipVersion _ = V4 instance IPAddrRepr Word128 where ipVersion _ = V6 -- and for convenience, maybe, instance (IPAddrRepr n) => IPAddrRepr (IPAddr n) where ipVersion (IPAddr n _) = ipVersion n Alternatively I have an inkling that you could play with GADTs. But the basic Haskell type system is surprisingly powerful itself! There might be a way to write what you want without extensions. It depends on exactly what you're trying to do. For some purposes we might need to change/add to have a data IPVersioned = V4 (IPAddr Word32) | V6 (IPAddr Word128) -Isaac