id summary reporter owner description type status priority milestone component version resolution keywords cc os architecture failure testcase blockedby blocking related differential wikipage
1772 GHC doesn't like 'inline' type function applications jpbernardy chak "{{{
{-# 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." bug closed normal 6.10 branch Compiler (Type checker) 6.9 fixed Unknown/Multiple Unknown/Multiple None/Unknown