- Reactive - Haskell.org

reactive (-glut) problems?
by Balazs Komuves 03 Dec '08

03 Dec '08

Dear All, I'm trying to get my hands wet with the reactive library, but already the simplest example I cooked up is failing to work properly (and leaks memory, and uses relatively lots of cpu time). The problem appears when I try to merge my two events with `mappend`. One event should exit on pressing ESC, the other draws colored circles on pressing the left mouse button. They work correctly separately. Could somebody explain me what's happening, or whether I'm making a basic mistake? The code is below, I hope the formatting survives the various email systems. I don't know if that matters or not, but I'm using OS X. Thanks, Balazs module Main where > > import Control.Monad > import Data.Monoid > > import FRP.Reactive > import FRP.Reactive.GLUT.Adapter > > import Graphics.Rendering.OpenGL hiding (normalize) > import Graphics.UI.GLUT hiding (normalize,Char) > > import System.Exit > > ------------------------------------------------------- > > nop :: Monad m => m () > nop = return () > > data Vec2 = Vec2 !Float !Float > > (&+) (Vec2 x1 y1) (Vec2 x2 y2) = Vec2 (x1+x2) (y1+y2) > > sinCosRadius a r = Vec2 (r * cos a) (r * sin a) > > instance Vertex Vec2 where > vertex (Vec2 x y) = vertex (Vertex2 x y) > > ------------------------------------------------------- > > display :: Action -> Action > display action = do > clear [ ColorBuffer , DepthBuffer ] > > siz@(Size xs ys) <- get windowSize > matrixMode $= Projection > loadIdentity > let q = fromIntegral xs / fromIntegral ys > r = 1 / q > if q >= 1 > then ortho 0 1 r 0 (-1) 1 > else ortho 0 q 1 0 (-1) 1 > viewport $= ( Position 0 0 , siz ) > matrixMode $= Modelview 0 > loadIdentity > > action > postRedisplay Nothing > swapBuffers > > data Col = RR | GG | BB > > nextCol RR = GG > nextCol GG = BB > nextCol BB = RR > > setCol RR = color (Color3 1 0 (0::Float)) > setCol GG = color (Color3 0 1 (0::Float)) > setCol BB = color (Color3 0 0 (1::Float)) > > drawWithCol col = do > setCol col > let center = Vec2 0.25 0.25 > radius = 0.1 > n = 32 > renderPrimitive TriangleFan $ do > vertex center > let phi j = 2*pi * fromIntegral j / fromIntegral n > forM_ [0..n] $ \i -> > vertex (center &+ sinCosRadius (phi i) radius) > > myUI :: UI -> Behaviour Action > myUI ui = uiB where > > mp = mousePosition ui > lb = leftButtonPressed ui > rb = leftButtonPressed ui > ky = keyPressed ui > > colE = mealy_ RR nextCol lb > drawE = fmap drawWithCol colE > > exitE = justE (fmap esc ky) where > esc k = case k of > Char '\ESC' -> Just exitSuccess > _ -> Nothing > > uiE = fmap display drawE `mappend` exitE > uiB = stepper nop uiE > > ------------------------------------------------------- > > main = do > initialize "alma" [] > initialWindowSize $= Size 512 384 > initialDisplayMode $= [ RGBAMode , WithDepthBuffer , DoubleBuffered ] > createWindow "reactive test" > adapt myUI >

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Problem cabal installing reactive 0.9.6
by Creighton Hogg 03 Dec '08

03 Dec '08

I got the following error when I attempted to use cabal install just a moment ago. The hackage page makes it look like it builds just fine, so I'm wondering if anyone else has seen this or if I've somehow borked my setup. src/FRP/Reactive/PrimReactive.hs:103:42: Ambiguous occurrence `zipWith' It could refer to either `Prelude.zipWith', imported from Prelude at src/FRP/Reactive/PrimReactive.hs:61:0-26 or `Data.Zip.zipWith', imported from Data.Zip at src/FRP/Reactive/PrimReactive.hs:85:0-14 src/FRP/Reactive/PrimReactive.hs:116:31: Ambiguous occurrence `zipWith' It could refer to either `Prelude.zipWith', imported from Prelude at src/FRP/Reactive/PrimReactive.hs:61:0-26 or `Data.Zip.zipWith', imported from Data.Zip at src/FRP/Reactive/PrimReactive.hs:85:0-14 src/FRP/Reactive/PrimReactive.hs:118:14: Ambiguous occurrence `zipWith' It could refer to either `Prelude.zipWith', imported from Prelude at src/FRP/Reactive/PrimReactive.hs:61:0-26 or `Data.Zip.zipWith', imported from Data.Zip at src/FRP/Reactive/PrimReactive.hs:85:0-14 src/FRP/Reactive/PrimReactive.hs:778:39: Ambiguous occurrence `zipWith' It could refer to either `Prelude.zipWith', imported from Prelude at src/FRP/Reactive/PrimReactive.hs:61:0-26 or `Data.Zip.zipWith', imported from Data.Zip at src/FRP/Reactive/PrimReactive.hs:85:0-14 src/FRP/Reactive/PrimReactive.hs:797:17: Ambiguous occurrence `zipWith' It could refer to either `Prelude.zipWith', imported from Prelude at src/FRP/Reactive/PrimReactive.hs:61:0-26 or `Data.Zip.zipWith', imported from Data.Zip at src/FRP/Reactive/PrimReactive.hs:85:0-14

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splitE => partitionE
by David Sankel 02 Dec '08

02 Dec '08

Would partitionE be a better name for splitE? I'm thinking that splitE could be a more general function that doesn't chop off the right hand side of an event. My proposal, by example: partitionE [(0,()), (5,())] [(2,()), (4,()), (6,()), (8,()), (10,())] => [ (0, ((), [(2,()), (4,())] )) , (5, ((), [(6,()), (8,()), (10,())])) ] splitE [(0,()), (5,())] [(2,()), (4,()), (6,()), (8,()), (10,())] => [ (0, ((), [(2,()), (4,()), (6,()), (8,()), (10,())])) , (5, ((), [(6,()), (8,()), (10,())])) ] Any objections? David -- David Sankel

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windowPoint function in Reactive/GLUT/SimpleGL.hs
by Peter Verswyvelen 01 Dec '08

01 Dec '08

The windowPoint function in Reactive/GLUT/SimpleGL.hs has the following comment: -- | Convert a window position to a logical X,Y. Logical zero is at the -- origin, and [size??]. -- -- TODO: this def is completely broken. What do I even want? Probably to -- go backward through the viewing transform to the XY plane. The function I made in the past for doing this is: windowPoint :: GL.Position -> IO (Double,Double)windowPoint pos(a)(GL.Position x y) = do viewport(a)(_,GL.Size _ height) <- get GL.viewport modelviewMatrix <- getMatrix $ GL.Modelview 0 projectionMatrix <- getMatrix $ GL.Projection let pos3 = GL.Vertex3 (fromIntegral x) (fromIntegral (height-y)) 0 GL.Vertex3 vx vy _ <- GLU.unProject pos3 modelviewMatrix projectionMatrix viewport return (vx,vy) where getMatrix :: GL.MatrixMode -> IO(GL.GLmatrix Scalar) getMatrix mode = get $ GL.matrix $ Just mode

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Is the code in makeTVal free of race conditions?
by Peter Verswyvelen 29 Nov '08

29 Nov '08

I'm looking at the makeTVal code: data TVal t a = TVal { timeVal :: (t,a), definedAt :: t -> Bool } makeTVal :: Clock TimeT -> MkFed (TVal TimeT a) amakeTVal (Clock getT _) = f <$> newEmptyIVar where f v = (TVal (readIVar v) (unsafePerformIO . undefAt), sink) where undefAt t = -- Read v after time t. If it's undefined, then it wasn't defined -- at t. If it is defined, then see whether it was defined before t. do -- ser $ putStrLn $ "sleepPast " ++ show t sleepPast getT t-- maybe True ((> t) . fst) <$> tryReadIVar v value <- tryReadIVar v case value of -- We're past t, if it's not defined now, it wasn't at t. Nothing -> return False -- If it became defined before t, then it's defined now. Just (t',_) -> return (t' < t) sink a = do t <- getT writeIVar v (t,a) I assume the sink function is called from a different thread than the one on which undefAt is called. Suppose a thread switch happens just before the (t,a) value is written to the IVar in sink a = do t <- getT writeIVar v (t,a) Lets call the t above t1. Now sleepPast getT t is evaluated on the other thread. sleepPast getT t Assume the parameter t passed to sleepPast is really close to t1 but larger than t1. Call it t2. So t1 < t2. Call t3 the time as evaluated by getT in the sleepPast function. So t1 < t2 < t3 (since t3 is read a after t1, and since the clock is serialized, this is the case I guess) Since t3 > t2, sleepPast will not call threadDelay, so it is not unlikely that a thread switch happens. But then value <- tryReadIVar v evaluates to Nothing, since the IVar is not written to yet. So undefAt will return False, although clearly t1 < t2 and so it should have returned True. I'm not sure if my reasoning is correct. But if it is, it would be solvable my making sure that getting the time from clock and writing it to the IVar is an atomic operation. Does any of the above make sense?

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reactive adapter for OpenAL
by Richard Smith 28 Nov '08

28 Nov '08

Hello list, I'm working on a reactive adapter for OpenAL, allowing sounds to be generated and played as Behaviour Double. It's a little slow, but working. You can get the source from http://metafoo.co.uk/darcs/resound Comments, constructive criticism and especially patches welcomed :) Thanks, Richard (IRC:lilac)

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Snapshotting a Behavior built with accumB seems to go wrong
by Eyal Lotem 27 Nov '08

27 Nov '08

It seems that going from Event(1) -> Behavior(2) -> Event(3) -> Behavior(4) is broken: http://trac.haskell.org/reactive/ticket/13 The first event(1), is for example a keyPressed, which is accumB'd into a Behavior(2). Then that Behavior is snapshotted(3) against a regular interval ticker (atTimes [0, gap..]), and then "stepper" is used to convert it to a behavior(4) again. The whole behavior(4) is broken and does not change at all, while the intermediate behavior(2) is just fine. Any idea what could cause this? Eyal

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Re: GTK + Reactive
by Levi Stephen 26 Nov '08

26 Nov '08

Hi, This is no longer a problem I managed to get this working by adding the following lines: updater <- mkUpdater (cGetTime clock) (return () `stepper` quitOnDestory windowDestroy) idleAdd (updater >> return True) Levi On Mon, Nov 24, 2008 at 10:30 PM, Levi Stephen <levi.stephen(a)gmail.com>wrote: > Hi, > > I'm trying to set up a simple program combining Reactive and GTK. I have > the program below so far, but mainQuit is never called. After looking at a > couple of adapters I tried adding the commented out line, but this didn't > work for me. > > I'm sure I've probably missed something, but I'm not sure what. > > Thanks, > Levi > > main = do > initGUI > > clock <- makeClock > > (windowDestroy, sink) <- makeEvent clock > > w <- windowNew > w `onDestroy` sink () > widgetShowAll w > > -- forkE (tSync clock) $ quitOnDestroy windowDestroy > > mainGUI > > quitOnDestroy :: Event () -> Event (IO ()) > quitOnDestroy e = fmap (const mainQuit) e > > tSync :: Clock TimeT-> ITime -> IO () > tSync clock t = sleepPast (cGetTime clock) (exact t) > >

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'stateE' --> 'mealy'
by Conal Elliott 25 Nov '08

25 Nov '08

I renamed 'stateE' and 'stateE_' to' mealy' and 'mealy_' in reactive-0.9.4 (just released). I've been meaning to change these names for a while now. I prefer these new names as being more clear & specific and connecting clearly to automata theory rather than to imperative programming. Please update your code if you use either function. David -- would you tweak the Events tutoria<http://netsuperbrain.com/blog/posts/introducing-reactive-events/>l accordingly? - Conal

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Transforming Behaviors
by Greg Fitzgerald 25 Nov '08

25 Nov '08

Should it be possible to write this: spinningTorusPair :: Double -> Behavior Geometry3 spinningTorusPair sz = uscale3 sz *% spinningG torusPair Instead of this: spinningTorusPair :: Double -> Behavior Geometry3 spinningTorusPair sz = (uscale3 sz *%) <$> spinningG torusPair That is, should a Behavior of something transformable be an instance of Transform as well? Has anyone tried to implement this instance? Thanks, Greg

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