Re: [Haskell-cafe] How to put a string into Data.Binary.Put
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
Re: [Haskell-cafe] How to put a string into Data.Binary.Put
Thanks a lot Gregory and Daniel, I think I'll go with the mapM_ (putWord8 . fromIntegral . ord) approach. -- Regards, Kashyap ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to put a string into Data.Binary.Put
Use one of the Char8 modules, depending on whether you want a strict or lazy bytestring: --- import qualified Data.ByteString.Lazy.Char8 as BS message :: BS.ByteString message = BS.pack SOME STRING --- See the docs at: http://hackage.haskell.org/packages/archive/bytestring/0.9.1.7/doc/html/Data-ByteString-Char8.html http://hackage.haskell.org/packages/archive/bytestring/0.9.1.7/doc/html/Data-ByteString-Lazy-Char8.html mapping over putWord8 is much slower than putting a single bytestring; if you want to put a string, pack it first: --- putString :: String - Put putString str = putLazyByteString (BS.pack str) -- alternative: probably faster import qualified Data.ByteString.Char8 as B putString :: String - Put putString str = putByteString (B.pack str) --- On Sat, Nov 6, 2010 at 05:30, C K Kashyap ckkash...@gmail.com 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] How can I convert the list of Put's such that it could be used in the Put monad? 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. -- Regards, Kashyap ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to put a string into Data.Binary.Put
On 11/6/10 6:38 AM, C K Kashyap wrote: Thanks a lot Gregory and Daniel, I think I'll go with the mapM_ (putWord8 . fromIntegral . ord) approach. If your string has any chance of containing Unicode characters then you will want to use the encode function in the module Codec.Binary.UTF8.String in the package utf8-string, so that the code becomes mapM_ putWord8 . encode Cheers, Greg ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
