Emil Melnikov
Recently I discovered for myself "monadLib" as an alternative for mtl-like packages. It seems that "monadLib" has better interface, but I'm quite confused with it's type classes: they have the monad type variable before the effect type variable (e.g. "ReaderM m i" instead of "ReaderM i m"). AFAIU, this ordering makes impossible to use these type classes in conjunction with GHC's cunning newtype deriving extension. Of course one can easily derive all instances using functionality provided by "MonadLib.Derive" module, but this is a boilerplate. Is there any way to avoid this boilerplate?
When discussing a similar issue with Manuel Chakravarty, he convinced me that cunning newtype deriving is actually rather bad in practice and shouldn't be used as there's a lack of proofs or some such (I can't remember the arguments, but I remember being convinced by them :p). -- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com IvanMiljenovic.wordpress.com