Try something like this: module Main where import Network.Socket main = withSocketsDo $ do -- Make a UDP socket s <- socket AF_INET Datagram defaultProtocol -- We want to listen on all interfaces (0.0.0.0) bindAddr <- inet_addr "0.0.0.0" -- Bind to 0.0.0.0:30000 bindSocket s (SockAddrInet 30000 bindAddr) -- Read a message of max length 1000 from some one (msg,len,from) <- recvFrom s 1000 putStrLn $ "Got the following message from " ++ (show from) putStrLn msg Does this help? As Stephan said, you missed the bind step. /jve On Sun, Jan 25, 2009 at 11:22 AM, Andrew Coppin <andrewcoppin@btinternet.com
wrote:
I'm trying to write a simple program that involves UDP. I was hoping something like this would work:
module Main where
import Network.Socket
main = withSocketsDo main2
main2 = do s <- socket AF_INET Datagram defaultProtocol putStrLn "Waiting..." x <- recv s 100 putStrLn x
Unfortunately, that doesn't work at all. It immediately throws an exception ("unknown error"). But then, the whole module seems to be completely undocumented. I managed to find a tiny amount of info online about the underlying C API, but I still don't get how the Haskell interface is supposed to be used. Any hints?
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