On Tue, Apr 9, 2013 at 6:34 PM, Ovidiu D
I would expect the following to work as well: main = Conduit.sourceList [1..14] $= Conduit.map show $= display $$ Conduit.sinkNull
display = Conduit.iterM putStrLn $= Conduit.iterM putStrLn
...but I get the compilation error: Couldn't match expected type `String' with actual type `()' Expected type: Conduit.Conduit String m0 a0 Actual type: Conduit.Source IO () In the second argument of `($=)', namely `display' In the first argument of `($$)', namely `Conduit.sourceList [1 .. 14] $= Conduit.map show $= display'
This looks to me like the monomorphism restriction kicked in and extended defaulting is turned on, so () got inferred? If so, {-# LANGUAGE NoMonomorphismRestriction #-} at the top of the file should help. (If this is actually in ghci, then that is almost certainly what happened; many people shut off the monomorphism restriction in ghci to avoid this annoyance.) -- brandon s allbery kf8nh sine nomine associates allbery.b@gmail.com ballbery@sinenomine.net unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net