Re: Socket library ghc 5.02.1

27 Nov 2001

      From: "Sigbjorn Finne" <sof@galconn.com>
	 Cc: <glasgow-haskell-users@haskell.org>
	 References: <200111220959.KAA29614@softwareag.com>
	 Date: Mon, 26 Nov 2001 12:30:47 -0800

		"Sven Eric Panitz" <sep@softwareag.com> writes:
	 > 
	 > It seems that the Socket library does still not work
	 > with ghc 5.02.1.
	 > I tried the simple test:
	 > 
	 > > main =
	 > >     do
	 > >     d <- connectTo "localhost" (PortNumber 80)
	 > >     hPutStr d "GET / HTTP/1.0\n\n"
	 > >     hFlush d
	 > >     c <- hGetContents d
	 > >     putStr c
	 > 
	 > On Windows2000 I get the known error:
	 > 
	 > *** Exception: does not exist
	 > Action: getProtocolByName
	 > Reason: no such protocol entry
	 > 

	 (You, of course, need to wrap up that code with Socket.withSocketDo
	 to start up WinSock first).

	 FYI, in case you're planning on doing socket programming with GHC-5.02
	 on a Win32 platform, stay away from using the higher-level Socket module,
	 since its IO.Handle based view of sockets is just broken. Stick with the
	 lower-level SocketPrim interface instead.

	 Specifically, stay away from using the following:

			* Socket. connectTo
			* Socket.accept
			* Socket.sendTo
			* Socket. recvFrom
			* SocketPrim.socketToHandle

	 --sigbjorn

Thanks for the help and valuable information. 

I tried the following little test, which stays away from
above functions:
...
module Main where
import BSD
import SocketPrim
import Socket (withSocketsDo)
main =  
 Socket.withSocketsDo
  (do
    protNum <- getProtocolNumber "tcp"
    s <- socket AF_INET Stream protNum
    hostAddr <- inet_addr "157.189.164.68"
    let sAddr =  (SockAddrInet (toEnum 8080) hostAddr)
    connect s sAddr
    i <- sendTo  s "GET / HTTP/1.0\r\n\r\n" sAddr
    (str,l,imsAddr) <- recvFrom s 1000
    putStr str
  )
But something I seem to be doing wrong.

During evaluation of 'recvFrom s 1000' I get the following
error message (consistently for unix and windows):

  Fail: SocketPrim.hsc:241: Non-exhaustive patterns in case

As the log of the webserver reveals the sendTo works fine.

Any idea what could be my problem?

Sven Eric