I wrote a combination reader/writer monad (a la the RWS monad in the mtl) and I find myself wanting to use multiple instances of it in the same stack of transformers. The functional dependencies prevent this from working out. The class is called MonadRW and the transformer is called RWT. I find myself wishing I could import the same module twice, but instead of having two names for the same entity, I want the definitions proper of the module to be duplicated: I want two separate MonadRW classes and two separate RWT transformers. Since the module integrates the MonadRW and RWT transformer with the mtl, I would then only need to lift the instances of the instantiated MonadRW classes through the other RWTs. I'm rather unfamiliar with Template Haskell, but it sounds like it might fit the bill. Although, if I recall correctly, instances and type declarations splicing are yet to be implemented in GHC? Does anyone have any advice how to do this? I'm envisioning some preprocessing. I'd like to know if someone has developed a tool for this already or if this path has been attempted. Thanks for your time, Nick PS - If this doesn't work out, I'm aware that I could use type-indexed products and coproducts to pull it off, but I think that would drastically reduce the number of people who could understand/maintain the code without having to learn such cool stuff.