# Pastebin uhtRxKN4
instance (Monad m, Reflex t) => HasSource t HydrationDomSpace (SourceT t HydrationDomSpace m) where
  fetchData queryE = pure never

instance (Monad m, Reflex t) => HasSource t StaticDomSpace (SourceT t StaticDomSpace m) where
  fetchData queryE = pure never

-- instance (Monad m, Reflex t) => HasSource t js (SourceT t js m) where
--   fetchData queryE = pure never

instance (Monad m, Reflex t, HasJSContext (Performable m), MonadJSM (Performable m), PerformEvent t m) => HasSource t GhcjsDomSpace (SourceT t GhcjsDomSpace m) where

  fetchData queryE = do
    performEvent $ toPerformable <$> queryE

    where

      toPerformable args = fetch xhrFetch args

      xhrFetch queryBS = do
        endpoint <- ask

        let req = xhrRequest "POST" endpoint $ def & xhrRequestConfig_sendData .~ BL.toStrict queryBS

        resultVar <- newEmptyMVar
        void $ newXMLHttpRequest req $ liftIO . putMVar resultVar
        resp <- takeMVar resultVar

        let body = case resp ^. xhrResponse_responseText of
              Nothing  -> error "boom"
              Just txt -> BL.fromStrict . T.encodeUtf8 $ txt

        pure body