Ok, by deleting all the examples I managed to install reactive-banana-wx. The Couter.hs example runs fine. I’m now trying to do a example where the value of a slider is posted to text box, but I can’t get it to work. event0 is for events that don’t ouput anything, but slider has a value.... what should I do ? {----------------------------------------------------------------------------- A slider and a text box ------------------------------------------------------------------------------} {-# LANGUAGE ScopedTypeVariables #-} -- allows "forall t. NetworkDescription t" import Graphics.UI.WX hiding (Event) import Reactive.Banana import Reactive.Banana.WX {----------------------------------------------------------------------------- Main ------------------------------------------------------------------------------} main:: IO() main = start $ do f <- frame [text := "A slider"] sl <- hslider f False 0 100 [] output <- staticText f [] set f [layout := margin 10 $ column 25 [widget sl, widget output]] let networkDescription :: forall t. NetworkDescription t () networkDescription = do esl <- event0 sl command let b = stepper 0 esl -- this doesn’t work off course... sink output [text :== show <$> b] network <- compile networkDescription actuate network thanks Miguel Negrão