On Saturday 06 November 2010 13:30:45, C K Kashyap wrote: > Hi, > I was trying to put a String in a ByteString > > import qualified Data.ByteString.Lazy as BS > message :: BS.ByteString > message = runPut $ do > let string="SOME STRING" > map (putWord8.fromIntegral.ord) > string -- this ofcourse generates [Put]
You'd want mapM_ (putWord8 . fromIntegral . ord) > > How can I convert the list of Put's such that it could be used in the > Put monad? sequence_ :: Monad m => [m a] -> m () if you want to use the results of the monadic actions, sequence :: Monad m => [m a] -> m [a] Often sequence and sequence_ are used for list resulting from a map, so there's mapM_ :: Monad m => (a -> m b) -> [a] -> m () mapM_ f xs = sequence_ (map f xs) mapM :: Monad m => (a -> m b) -> [a] -> m [b] mapM f xs = sequence (map f xs) > > For now I used the workaround of first converting the string to > ByteString like this - > > stringToByteString :: String -> BS.ByteString > stringToByteString str = BS.pack (map (fromIntegral.ord) str) > > and then using putLazyByteString inside the Put monad. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
