[Haskell-beginners] Issue installing reactive-banana-5.0.0.1

[Miguel Negrao]

A 05/05/2012, às 15:26, Miguel Negrao escreveu:
> 
> Hum, that’s not exactly what I wanted. So if it’s the first event just let it through, and then filter it. If it’s not the first event, then do the inversion (1-x) or not depending on the last outputted value, and then filter it.
> An input of 
> 	[[0.9],[0.5],[0.1],[0.9],[0.9]]
> should produce
> 	[[0.9],[],[0.9],[0.1],[0.9]]
> 
> The following code is not correct but it’s closer to what I described:
> 
> module Main where
> 
> import Reactive.Banana
> 
> main :: IO()
> main = do
>        list <- interpretModel example [[0.9],[0.3],[0.4],[0.15],[0.87]]
>        putStrLn $ show list   
> 
> example :: Event t Double -> Event t Double
> example e = filterede2
>        where
>        filterede2 = filterE (\x->between x 0.0 0.2 && between x 0.8 1.0)  e2
>        e2 = f <$> bIsFirst <@> e <@> e2
> 
>        bIsFirst = stepper True $ False <$ e
> 
>        between x a b = a < x && x < b
> 
>        f True x y = x
>        f False x y
>                | between y 0.8 1.0 = 1 - x
>                | otherwise = x

Actually I just spotted that the filtering should not be done after the “recursive” part. It should be something more like:

> example e = e2 where e2 = filterE (\x->between x 0.0 0.2 && between x 0.8 1.0) (f <$> bIsFirst <@> e <@> e2)

best,
Miguel Negrão