[Haskell-cafe] Is this a correct explanation of FRP?
apfelmus at quantentunnel.de
Fri Mar 30 14:33:51 CEST 2012
Michael Snoyman wrote:
> First you state that we shouldn't use `union` for the `ePitch` Event,
> and then you used it for `bOctave`. Would it be more efficient to
> implement bOctave as someting like:
> eOctave :: Event t (Int -> Int)
> eOctave =
> filterJust toStep <$> eKey
> toStep '+' = Just (+ 1)
> toStep '-' = Just (subtract 1)
> toStep _ = Nothing
> bOctave :: Behavior t Octave
> bOctave = accumB 0 eOctave
It's largely a matter of efficiency in notation rather than efficiency
> Also, I'm left wondering: how would you create a new event stream in
> the first place? You're telling us to just rely on `eKey`, which is
> fair, but a great follow-up would demonstrate building it. Looking
> through the docs I found `newEvent`, but I'm not quite certain how I
> would combine it all together.
It's best to look at the example for that and peruse the documentation
in Reactive.Banana.Frameworks in case something is unclear.
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