fix stanza ID generator

source/Network/Xmpp/Concurrent.hs

@@ -113,12 +113,13 @@ newSession stream config = runErrorT $ do
                                                           ]
     (kill, wLock, streamState, readerThread) <- ErrorT $ startThreadsWith stanzaHandler eh stream
     writer <- lift $ forkIO $ writeWorker outC wLock
+    idGen <- liftIO $ sessionStanzaIDs config
     return $ Session { stanzaCh = stanzaChan
                      , outCh = outC
                      , iqHandlers = iqHandlers
                      , writeRef = wLock
                      , readerThread = readerThread
-                     , idGenerator = sessionStanzaIDs config
+                     , idGenerator = idGen
                      , streamRef = streamState
                      , eventHandlers = eh
                      , stopThreads = kill >> killThread writer

source/Network/Xmpp/Types.hs

@@ -1100,7 +1100,7 @@ data SessionConfiguration = SessionConfiguration
       -- | Handler to be run when the session ends (for whatever reason).
     , sessionClosedHandler :: XmppFailure -> IO ()
       -- | Function to generate the stream of stanza identifiers.
-    , sessionStanzaIDs :: IO StanzaID
+    , sessionStanzaIDs :: IO (IO StanzaID)
     , extraStanzaHandlers   :: [StanzaHandler]
     }
 
@@ -1109,10 +1109,10 @@ instance Default SessionConfiguration where
                                , sessionClosedHandler = \_ -> return ()
                                , sessionStanzaIDs = do
                                      idRef <- newTVarIO 1
-                                     atomically $ do
+                                     return . atomically $ do
                                          curId <- readTVar idRef
                                          writeTVar idRef (curId + 1 :: Integer)
-                                         return . read. show $ curId
+                                         return . StanzaID . Text.pack . show $ curId
                                , extraStanzaHandlers = []
                                }