On Fri, Jun 4, 2010 at 8:02 PM, Pete Chown <1@234.cx> wrote:
I've been trying to get in touch with the maintainers of the Binary package, to report an issue. When I emailed the addresses given on Hackage, I got an automated response saying I had used an address that was no longer current.
I don't want to put pressure on anyone to fix my bug -- I didn't pay anything for Binary, so it wouldn't be fair for me to have that kind of expectation. At the same time, I don't really want my bug report to go missing just because someone's email address has changed. Does anyone know who I should be talking to? Or is there a bug tracker for the Hackage packages somewhere?
I noticed this problem when I ran into some trouble with the network-dns package. It would hang up as soon as I tried to send a query. Eventually I traced the problem to the binary module, and reduced it to this short test case:
module Main where
import qualified Data.Binary.Get as G import qualified Data.ByteString.Lazy as B
main = do urandom <- B.readFile "/dev/urandom" let urandomParser :: G.Get [Int] urandomParser = do v <- G.getWord32be rest <- urandomParser return $ fromIntegral v : rest seeds = G.runGet urandomParser urandom
print $ take 4 seeds
This issue was discussed on the list before. Get monad definition was changed in binary 0.5.0.2. It was made strict and evaluation of result of runGet is forced. This increased performance but broke programs which relies on lazyness to work. Here is code I use to work around this issue:
runGetStream :: Get a -> ByteString -> [a] runGetStream getter bs = unfoldr step bs where step bs = case runGetState getOne bs 0 of (Nothing, _, _ ) -> Nothing (Just x, bs', off') -> Just (x, bs') getOne = do empty <- isEmpty if empty then return Nothing else Just <$> getter ... seeds = runGetStream (fromInteger <$> getWord64be) urandom