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{-# LANGUAGE OverloadedStrings #-}
-- Echo client program
module Main (main) where
import qualified Control.Exception as E
import qualified Data.ByteString.Char8 as C
import Network.Socket
import Network.Socket.ByteString (recv, sendAll)
main :: IO ()
main = runTCPClient "127.0.0.1" "3000" $ \s -> do
sendAll s "Hello, world!"
msg <- recv s 1024
putStr "Received: "
C.putStrLn msg
-- from the "network-run" package.
runTCPClient :: HostName -> ServiceName -> (Socket -> IO a) -> IO a
runTCPClient host port client = withSocketsDo $ do
addr <- resolve
E.bracket (open addr) close client
where
resolve = do
let hints = defaultHints { addrSocketType = Stream }
head <$> getAddrInfo (Just hints) (Just host) (Just port)
open addr = do
sock <- socket (addrFamily addr) (addrSocketType addr) (addrProtocol addr)
connect sock $ addrAddress addr
return sock
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