Occasionally it's useful to get a little information about a type's constructor (especially its name, module, or source package), without needing a Typeable instance for the type itself. I came up with this rather simple way, but I'm wondering if something like this already exists on Hackage. #if __GLASGOW_HASKELL__ < 710 {-# language OverlappingInstances #-} #endif ... import Data.Typeable class OuterTypeable a where -- | Get the 'TypeRep' corresponding to the outermost constructor -- of a type. getConTR :: proxy a -> TypeRep #if __GLASGOW_HASKELL__ >= 708 instance # if __GLASGOW_HASKELL__ >= 710 {-# OVERLAPPING #-} # endif OuterTypeable f => OuterTypeable (f a) where getConTR _ = getConTR (Proxy :: Proxy f) instance Typeable a => OuterTypeable a where getConTR = typeRep #else -- Before GHC 7.8, we didn't have polykinded Typeable, so things were -- rather less nice. instance Typeable a => OuterTypeable a where getConTR _ = typeOf (undefined :: a) instance Typeable1 p => OuterTypeable (p a) where getConTR _ = typeOf1 (undefined :: p a) [...] instance Typeable7 p => OuterTypeable (p a b c d e f g) where getConTR _ = typeOf7 (undefined :: p a b c d e f g) #endif