Standalone deriving using template haskell
Currently, there seems to be no support for standalone deriving in TemplateHaskell:
Prelude Data.Typeable Language.Haskell.TH> :set -XStandaloneDeriving Prelude Data.Typeable Language.Haskell.TH> data Weird a (b :: * -> * -> *) c = Weird Prelude Data.Typeable Language.Haskell.TH> runQ $ [d| deriving instance Typeable Weird |] 
The library typeable-th can already generate Typeable instances using TH for GHC 7.4 and 7.6. To add support for GHC 7.8 in a way that the user doesn't have to care about the version, there has to be a way to make Typeable instances via TH in GHC 7.8. This is currently impossible, but with StandaloneDeriving support for TH, it would be possible.