The maybe monad with IO?

connection.hs

connect_uri :: U.URI -> Identity -> IO (Maybe Socket)
connect_uri uri id = do
    auth <- U.uriAuthority uri
    sock <- socktype
    let host = U.uriRegName auth
    let port = U.uriPort auth
    return $ connect host port sock id
    where socktype
            | U.uriScheme uri == "tcp:" = Just S.Stream
            | otherwise = Nothing

connect :: S.HostName -> S.ServiceName -> S.SocketType -> Identity -> IO Socket
connect servaddr servport socktype id = do
  addrinfos <- S.getAddrInfo (Just S.defaultHints) (Just servaddr) (Just servport)
  let servinfo = head addrinfos
  sock <- S.socket (S.addrFamily servinfo) socktype S.defaultProtocol
  S.connect sock (S.addrAddress servinfo)
  return $ Client sock