GHC doesn't like 'inline' type function applications

[jpbernardy]

{-# LANGUAGE TypeFamilies #-}

import Prelude hiding (foldl, foldr, foldl1, foldr1, mapM_, sequence_,
		elem, notElem, concat, concatMap, and, or, any, all,
		sum, product, maximum, minimum)
import Data.Monoid

type family Element t

class Foldable t where
        foldMap :: Monoid m => (Element t -> m) -> t -> m

	foldr :: (Element t -> b -> b) -> b -> t -> b
	-- foldr :: Element t ~ a => (a -> b -> b) -> b -> t -> b
	foldr f z t = appEndo (foldMap (Endo . f) t) z

GHC chokes on the above module. If the signature of foldr is replaced by the commented one, GHC is happy. It seems to me that the two expressions should be equivalent.

[simonmar]

We're not advertising type functions as part of 6.8.

[chak]

Works now in the HEAD.