This is a bug in GHC. See: http://hackage.haskell.org/trac/ghc/ticket/2267 I have the same problem in several of my source files. :-( Michael Snoyman wrote:
I was writing code similar to the following and compiling with "-Wall -Werror." Clearly I *am* using Data.ByteString for the function signatures.
{-# OPTIONS_GHC -fwarn-unused-imports -Werror #-} import qualified Data.ByteString as B import qualified Data.ByteString.UTF8 as BU
toString :: B.ByteString -> String toString = BU.toString
fromString :: String -> B.ByteString fromString = BU.fromString
main :: IO () main = putStrLn $ toString $ fromString "Hello World!"
The warning I get is:
Unused.hs:2:0: Warning: Module `Data.ByteString' is imported, but nothing from it is used, except perhaps instances visible in `Data.ByteString' To suppress this warning, use: import Data.ByteString()
Am I doing something wrong or is this a bug in GHC?
Thanks, Michael
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