Re: [Haskell-cafe] [ANN] frpnow-0.12

Atze, I have a question about Streams. In the Paper Impl the following code: newtype Stream a = S { next :: B (E a) } catMaybesStream :: Stream (Maybe a) -> Stream a catMaybesStream (S s) = S loop where loop = do e <- s join <$> plan (nxt <$> e) -- nxt :: Maybe a -> B (E a) nxt (Just a) = return (return a) nxt Nothing = loop Which I understand. And in the library the following code: newtype EvStream a = S { getEs :: Behavior (Event [a]) } catMaybesEs :: EvStream (Maybe a) -> EvStream a catMaybesEs s = S $ loop where -- loop :: Behavior (Event [a]) loop = do e <- getEs s join <$> plan (nxt <$> e) nxt l = case catMaybes l of [] -> loop l -> return (return l) I assume the new type EvStream the intent is for the stream of ‘a’ to be an array rather than a recursive data structure, based on the name ‘getEs’. But, catMaybeEs is written like the paper version, suggesting it is a recursive data structure arrays. My goal is to write an integrator for a stream, such that the type signature is: EvStream (Double,Double) -> EvStream (Double) where the tuple is (data, time) and the result is (integratedData) and I modeled the function catMaybeEs, but it is not working. So I want to understand the general way to handle the stream in catMaybesEs. Mike

On Jul 15, 2015, at 7:25 AM, Atze van der Ploeg wrote:

Dear Cafe, We have released the (nearly) first version of FRPNow, the functional reactive programming library based on the ICFP 2015 paper "Principled Practical FRP: Forget the Past, Change the Future, FRPNow!" (https://www.reddit.com/r/haskell/comments/3ai7hl/principled_practical_frp_fo... https://www.reddit.com/r/haskell/comments/3ai7hl/principled_practical_frp_fo...) The main package: http://hackage.haskell.org/package/frpnow http://hackage.haskell.org/package/frpnow Examples: https://github.com/atzeus/FRPNow/tree/master/Examples https://github.com/atzeus/FRPNow/tree/master/Examples Gloss interoperability: http://hackage.haskell.org/package/frpnow-gloss http://hackage.haskell.org/package/frpnow-gloss GTK interoperability: http://hackage.haskell.org/package/frpnow-gtk http://hackage.haskell.org/package/frpnow-gtk (hackage doesn't like the newer GTK docs, so you can read the docs at http://www.cse.chalmers.se/~atze/frpnow-gtk/ http://www.cse.chalmers.se/~atze/frpnow-gtk/ )

Cheers,

Atze _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe