An example of performEventAsync use Reflex

perfomEventAsync.hs

performHash :: (MonadWidget t m) => (Either String Hash -> IO ()) -> Event t Text -> m (Event t (Either String Hash))
performHash cb e = do
  evHash <- performEventAsync $ ffor e $ \p cb -> void $ newHash p $ liftIO . cb
  return evHash
  where
    newHash p = liftIO . hash (defaultOptions p "some_salt")