Hi, Recent GHC head on 32bit Linux cannot build conduit-1.0.9.2. (See the attached log.) A while ago, GHC head on 32bit Linux could build it. The same GHC head on 64bit Linux can build it. Michael Snoyman suggested me to add ImpredicativeTypes. When I added it to the Internal.hs, GHC head on 32bit Linux can build it. And he said to other released GHCs can build it. Actually, GHC 7.4.2 on 32bit Linux can build it. He believes that this is a bug of GHC head (on 32bit Linux). Any information? Note that conduit-1.0.9.3 already includes ImpredicativeTypes. --Kazu Building conduit-1.0.9.2... Preprocessing library conduit-1.0.9.2... [2 of 8] Compiling Data.Conduit.Internal ( Data/Conduit/Internal.hs, dist/build/Dat a/Conduit/Internal.o ) Data/Conduit/Internal.hs:211:105: Cannot instantiate unification variable ‛b0’ with a type involving foralls: (forall a. m1 a -> n1 a) -> ConduitM i o m1 b1 -> ConduitM i o n1 b1 Perhaps you want ImpredicativeTypes In the expression: GHC.Exts.coerce (hoist :: (forall (a :: *). m a -> n a) -> Pipe i i o () m b -> Pipe i i o () n b) :: forall (m :: * -> *) (b :: *) (n :: * -> *). Monad m => (forall (a :: *). m a -> n a) -> ConduitM i o m b -> ConduitM i o n b In an equation for ‛hoist’: hoist = GHC.Exts.coerce (hoist :: (forall (a :: *). m a -> n a) -> Pipe i i o () m b -> Pipe i i o () n b) :: forall (m :: * -> *) (b :: *) (n :: * -> *). Monad m => (forall (a :: *). m a -> n a) -> ConduitM i o m b -> ConduitM i o n b