So below is something I discovered that seems very strange. If you run the following code as is, it will run & you'll get stuck in the already documented integral loop. If you replace the use of events in main with events', the program consumes all available memory & locks up hard. I know I'm horribly abusing Reactive here, but I don't see why it should fail _so_ ungracefully. Cheers, Creighton import FRP.Reactive import FRP.Reactive.LegacyAdapters import Control.Concurrent import Control.Monad x :: Event () -> Behavior Double x e = b where b = integral e b events :: Event () events = atTimes [0.1,0.2] events' :: Event () events' = once events schedule a = threadDelay 100000 >> a main = do c <- makeClock u <- mkUpdater (cGetTime c) (fmap print $ x events) forever $ schedule u