Re: different flavours of Monad Template Library

I have uploaded these to hackage. The packages are: transformers: monad transformers, operations and liftings. This is all Haskell 98, and be used on its own, or as a base for packages defining monad classes. monads-fd: monad classes using functional dependencies, with instances for the transformers in the transformers package. This is mostly backwards-compatible with mtl. monads-tf: monad classes using type families, with instances for the transformers in the transformers package. This is mostly backwards-compatible with mtl-tf.