On 03/08/2010 10:45 PM, Wolfgang Jeltsch wrote: > The point is, of course, that such conversions are not only possible for > binary operations but for arbitrary values and that these conversions are > done > by a single generic function conv. I don’t think it would be possible to > implement conv without generalized newtype deriving. > > Any thoughts? >
Hi Wolfgang, it's not exactly the same, but... > import Control.Applicative > > newtype Wrapped a = Wrap a deriving Show > > instance Functor Wrapped where > fmap f (Wrap x) = Wrap $ f x > > instance Applicative Wrapped where > pure = Wrap > (Wrap f) <*> (Wrap x) = Wrap $ f x > > convBinOp :: (a -> a -> a) -> (Wrapped a -> Wrapped a -> Wrapped a) > convBinOp op x y = pure op <*> x <*> y Best regards, Steffen _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
