----------------------------------------------------------------------------- -- | -- Module : Network.Stream -- Copyright : See LICENSE file -- License : BSD -- -- Maintainer : Ganesh Sittampalam <ganesh@earth.li> -- Stability : experimental -- Portability : non-portable (not tested) -- -- An library for creating abstract streams. Originally part of Gray's\/Bringert's -- HTTP module. -- -- * Changes by Robin Bate Boerop <robin@bateboerop.name>: -- - Removed unnecessary import statements. -- - Moved Debug code to StreamDebugger.hs -- - Moved Socket-related code to StreamSocket.hs. -- -- * Changes by Simon Foster: -- - Split Network.HTTPmodule up into to separate -- Network.[Stream,TCP,HTTP] modules ----------------------------------------------------------------------------- module Network.Stream ( Stream(..) , ConnError(..) , Result , bindE , fmapE , failParse -- :: String -> Result a , failWith -- :: ConnError -> Result a , failMisc -- :: String -> Result a ) where import Control.Monad.Error data ConnError = ErrorReset | ErrorClosed | ErrorParse String | ErrorMisc String deriving(Show,Eq) instance Error ConnError where noMsg = strMsg "unknown error" strMsg x = ErrorMisc x -- in GHC 7.0 the Monad instance for Error no longer -- uses fail x = Left (strMsg x). failMisc is therefore -- used instead. failMisc :: String -> Result a failMisc x = failWith (strMsg x) failParse :: String -> Result a failParse x = failWith (ErrorParse x) failWith :: ConnError -> Result a failWith x = Left x bindE :: Result a -> (a -> Result b) -> Result b bindE (Left e) _ = Left e bindE (Right v) f = f v fmapE :: (a -> Result b) -> IO (Result a) -> IO (Result b) fmapE f a = do x <- a case x of Left e -> return (Left e) Right r -> return (f r) -- | This is the type returned by many exported network functions. type Result a = Either ConnError {- error -} a {- result -} -- | Streams should make layering of TLS protocol easier in future, -- they allow reading/writing to files etc for debugging, -- they allow use of protocols other than TCP/IP -- and they allow customisation. -- -- Instances of this class should not trim -- the input in any way, e.g. leave LF on line -- endings etc. Unless that is exactly the behaviour -- you want from your twisted instances ;) class Stream x where readLine :: x -> IO (Result String) readBlock :: x -> Int -> IO (Result String) writeBlock :: x -> String -> IO (Result ()) close :: x -> IO () closeOnEnd :: x -> Bool -> IO () -- ^ True => shutdown the connection when response has been read / end-of-stream -- has been reached.