Am Dienstag 27 Oktober 2009 16:47:12 schrieb Thomas DuBuisson:
Iain, If you wanted to make sure it didn't have to do with ghci then you should have compiled the original code, not tested different functions. The code you provided works fine compiled and I too am curious what is going on when you run it in ghci.
Thomas
Look at the sources: hGetLine :: Handle -> IO ByteString #if !defined(__GLASGOW_HASKELL__) hGetLine h = System.IO.hGetLine h >>= return . pack . P.map c2w #else hGetLine h = wantReadableHandle "Data.ByteString.hGetLine" h $ \ handle_ -> do case haBufferMode handle_ of NoBuffering -> error "no buffering" _other -> hGetLineBuffered handle_ where ... So, in ghci, stdin isn't buffered and ByteString can't cope with that. Why exactly, I don't know. Change code to main = hSetBuffering stdin LineBuffering >> B.getLine >>= B.putStrLn and it works.