I don't think this is possible in plain Haskell 98. It is possible in Generic Haskell, see: http://www.generic-haskell.org/ [...] Generic Haskell's type system is sufficient.
Is it possible using dependent types?
I would expect so.
I have been looking to Generic Haskell and it may be possible to define a generic map function like: mapN :: (a1 -> b1) -> ... -> (aN -> bN) -> f a1 ... aN -> f b1 ... bN However, I still don't know how could I define something like:
data FixN1 f1 ... fN = InN1 (f1 (FixN1 f1 ... fN) ... (FixNN f1 ... fN)) ... data FixNN f1 ... fN = InNN (fN (FixN1 f1 ... fN) ... (FixNN f1 ... fN))
I think that I would need dependent types, because I want to define a number of data types that depend on a given natural...any suggestions? Best regards, Gonzalo Flores