#1772: GHC doesn't like 'inline' type function applications
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Reporter: jpbernardy | Owner:
Type: bug | Status: new
Priority: normal | Milestone: 6.8.1
Component: Compiler (Type checker) | Version: 6.9
Severity: normal | Keywords:
Difficulty: Unknown | Os: Unknown
Testcase: | Architecture: Unknown
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{{{
{-# 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.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1772>
GHC <http://www.haskell.org/ghc/>
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