- Reactive - Haskell.org

Fwd: Auto-discard notification
by Conal Elliott 24 Aug '10

24 Aug '10

Oops. The list's spam-filter tossed this note. ---------- Forwarded message ---------- From: Alexander Foremny <alexanderforemny(a)googlemail.com> To: reactive(a)haskell.org Date: Tue, 24 Aug 2010 10:14:11 +0200 Subject: whenE uses much memory Hello, I am trying to write a simple 2D tower defense game using reactive and reactive-glut. I am spawning a wave of creeps that walk around the map and when there are no creeps on the map, I'd like to spawn the next wave. However, I cannot predict at which time there will be no creeps on the maps since each creature might move with different speed. To realize switching anyway I thought I could poll the number of creeps and switch when the number is zero. With that solution I am having serious performance problems. Here's the relevant code: > data World = World { ... } > > wave1 :: Behavior World > > wave2 :: Behavior World > > worldB = wave1 `switcher` fmap (const wave2) (whenE (zeroCreeps wave1) pollE) > where pollE = atTimes [1..] > > zeroCreeps :: Behavior World -> Behavior Bool When running worldB from main I can see the program's memory usage increasing and everything becomes very unresponsive. It seems as if whenE is accumalating all the occurences of the event. The problem seems to boil down to snapshot having the same behavior. > snapshot (pure False) (atTimes [1..]) This piece of code uses very much memory either. Is this due to reactive being broken (I read that somewhere) or is my solution just no solution at all? I am using ghc 6.12.1 with reactive 0.11.5 and reactive-glut 0.1.9. Regards Alexander Foremny

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An adapter for SDL
by Facundo Domínguez 05 Aug '10

05 Aug '10

Dear list: I've been trying to make an adapter for SDL, and it looks like I could have found some sort of bug. My test program leaks memory as it runs and does not react to clicks, but I cannot figure out why. I've tested this on Mac Leopard with ghc-6.12.1 and debian lenny with ghc-6.12.3. Here's the code: module Adapter where import qualified Graphics.UI.SDL as SDL import Control.Monad(liftM) import FRP.Reactive import FRP.Reactive.LegacyAdapters(makeClock,makeEvent,Sink,cGetTime,mkUpdater) import qualified Graphics.UI.SDL as SDL -- |Configures a Behavior to run. The first return 'IO' action should be called -- to update the screen. The second return 'IO' action must be called -- regularly to poll for events. configSDLBehavior :: (Event SDL.Event -> Behavior (IO ())) -> IO (IO (), IO ()) configSDLBehavior f = do clock <- makeClock (evSink,evs) <- makeEvent clock upd<-mkUpdater (cGetTime clock) (f evs) return (upd, getNextEvents 30 >>= mapM_ evSink) -- |Creates an source for sdl events and the 'IO' action that must be called -- regularly to poll for events. sdlEvents :: IO (Event SDL.Event, IO ()) sdlEvents = do clock <- makeClock (evSink,evs) <- makeEvent clock return (evs, getNextEvents 30 >>= mapM_ evSink) -- |@getNextEvents n@ polls for at most the next n events. getNextEvents :: Int -> IO [SDL.Event] getNextEvents n | n<=0 = return [] | otherwise = do ev<-SDL.pollEvent case ev of SDL.NoEvent -> return [] _ -> liftM (ev:)$ getNextEvents (n-1) ----------- And here is my test program: measureFPS :: IO Int -> IO () measureFPS frame = do t0<-SDL.getTicks n<-frame t1<-SDL.getTicks putStr$ show (toEnum n/ (toEnum (fromEnum (t1-t0))/1000)) ++ "\n" testB :: IO () -> Event SDL.Event -> Behavior (IO ()) testB quit evs = return () `stepper` fmap (pure quit) (filterE isKeyDown evs) isKeyDown e(a)(SDL.KeyDown _) = True isKeyDown e = False main = SDL.withInit [SDL.InitVideo]$ do screen <- SDL.setVideoMode 640 480 8 [SDL.SWSurface,SDL.AnyFormat] SDL.setCaption "Test" "" SDL.enableUnicode True quitv <- newIORef False (upd,poll) <- configSDLBehavior (testB (writeIORef quitv True)) measureFPS (loop 0 quitv upd poll) where loop n quitv upd poll | seq n True = do b <- readIORef quitv if b then return n else do poll SDL.delay 10 -- threadDelay 10000 upd loop (n+1) quitv upd poll Best, Facundo

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SDL ?
by Paul Brauner 18 Jul '10

18 Jul '10

Hello, I've just written my first reactive program which is a subtitles player. Following the FPS tutorial and with the help of listE it was really simple and natural! The problem I'm facing now is that fieldtrip rendering of fonts is not very readable, and I would like to use my program for real. I've been able to reproduce the same program with Yampa and SDL, which renders fints fine, but the pure part is not as elegant as the reactive version. So I would like to combine best of both worlds and use reactive with SDL. >From what I've seen there is no SDL adapter out there but I'd like to know if there is somewhere some example of an IO adapater or similar. Regards, Paul

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Problem with reactive-glut-0.1.9 on GHC 6.12.1
by Tom Poliquin 30 May '10

30 May '10

My student and I recently published four Reactive demos at, http://formicite.com/dopage.php?frp/frp.html All four work well on GHC 6.10 but one user had trouble with the two GLUT demos on GHC 6.12.1. We have fixed our modules and hacked a fix for reactive-glut (which we have included in our code just to get it working again). Most of the issues revolve around GLdouble and Double. To get it working we changed one line of code in SimpleGL.hs 117c117 < f maxZ z = realToFrac (z - (maxZ `div` 2)) / 100 --- > f maxZ z = realToFrac (z - (((fromIntegral maxZ)::GLint) `div` 2)) / 100 and removed 'Test.hs' requirement from the cabal setup as we weren't able to figure out how to fix it. Here's a snippit of our ghc-pkg list .. .. .. GLURaw-1.1.0.0 GLUT-2.2.2.0 HTTP-4000.0.8 MemoTrie-0.4.7 ObjectName-1.0.0.0 OpenGL-2.4.0.1 OpenGLRaw-1.1.0.1 .. .. .. reactive-0.11.4 reactive-glut-0.1.9 unamb-0.2.2 vector-space-0.6.2 zlib-0.5.2.0 .. .. .. Note: On the website the downloads labeled '...V2' are the ones with the hacks. Any thoughts appreciated on how to proceed. Thanks, Tom and Tony

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Re: [Haskell] Re: [Haskell-cafe] Work on Video Games in Haskell
by Ryan Trinkle 26 May '10

26 May '10

Hi guys, I don't think this licensing issue will be a problem for us. It's not clear to me that our game violates this new term, and we certainly don't violate any of the principles Steve Jobs used to justify it. If Apple wants to reject our app, they already have a variety of excuses at their disposal, as they've demonstrated on many occasions. Frankly, it'd be their loss; Android is now the fastest-growing smartphone market, and we'll be more than happy to focus on it (and other friendlier markets) if Apple's not interested in having our product on their platform. Ryan Trinkle iPwn Studios On Wed, May 26, 2010 at 4:18 AM, Brandon S. Allbery KF8NH < allbery(a)ece.cmu.edu> wrote: > On May 26, 2010, at 04:14 , David Virebayre wrote: > >> On Wed, May 26, 2010 at 9:58 AM, Brandon S. Allbery KF8NH >> <allbery(a)ece.cmu.edu> wrote: >> >>> You might want to reread that license agreement. Specifically: >>> >> >> Ah, yes. Ouch, that's abusive. >> Can they tell the difference though ? >> > > > I suspect GHC-generated code is fairly distinctive even as machine code. > But they don't have to go to that extent; all they have to do is use Google > to find this thread. :( > > > -- > brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allbery(a)kf8nh.com > system administrator [openafs,heimdal,too many hats] allbery(a)ece.cmu.edu > electrical and computer engineering, carnegie mellon university KF8NH > > > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > >

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Re: [reactive] Time leak problem with integral
by Limestraël 15 May '10

15 May '10

It leaks with me too. It's the same problem I'm having with my Pong attempt (see my post http://www.haskell.org/pipermail/reactive/2010-May/000337.html) The more often the integration event ticks, the quicklier the program time-leaks. I'm also using reactive 0.11.4 and GHC 6.12.1. I'm running Ubuntu 9.10 64bits version. Doesn't matter whether I use -O2 or not. > Hi folks, > I've got stacked now because of a time leak problem with integral. > The following program leaks CPU-time gradually: >* import FRP.Reactive *>* import FRP.Reactive.LegacyAdapters *>* import Control.Applicative * >* type Velocity = Double *>* type Position = Double * >* data Car = Car { vel :: Velocity, pos :: Position } deriving Show * >* velocity :: Behavior Velocity *>* velocity = 1 * >* position :: Behavior Position *>* position = integral (atTimes [0, 0.5 ..]) velocity * >* car :: Behavior Car *>* car = Car <$> velocity <*> position * >* main :: IO () *>* main = adaptE $ print <$> car `snapshot_` atTimes [0, 0.5..] * > 1) why is the leak happen? > 2) how can I fix this problem? > Some more detailed informations: > * reactive 0.11.4 > * GHC 6.12.1 > * Gentoo Linux (2.6.32-tuxonice, x86_64) > * compiled with or without -O2 flag > Thanks, > -- > Mitsutoshi Aoe

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A pong and integrate
by Limestraël 15 May '10

15 May '10

Hello, As a newbie with reactive, I'm trying to make a simple example, namely a pong. But I'm stuck with the paddle animation. Here is a how I proceed : A paddle: data Paddle = Paddle { paddleCol :: Double, paddleCenter :: Behavior Double } The paddle moves along a column, so only it's Y coordinate changes. paddleCenter is the Y coordinate of its center. This is how I create a paddle: data Direction = PaddleUp | PaddleDown | PaddleStill deriving (Eq, Show) newPaddle :: Behavior Direction -> Double -> Paddle newPaddle direction column = let position = fmap ((initY ^+^)) $ integral *beat* $ fmap ((speed *) . factor) direction factor PaddleUp = -1 factor PaddleDown = 1 factor _ = 0 speed = 50 -- pixels per second initY = 400 -- suppose we have a 800x600 window: paddle is right at the middle *beat = atTimes [0, 0.01..]* in Paddle column position Basically, a paddle is driven by a behavior which tells him to go up, down or to stand still. My problem is with the tuning of the beat, a ticker event which is used for the integration. How do I have to think ? - My speed is in pixels/second, so it has to tick every second? (atTime [0, 1..]) - My app will run at 60fps, so it has to tick 60 times per second? (atTime [0, 1/60..]) The main program (I'm not using any graphics library, just getting keys ('u' for up, 'd' for down) and displaying the current paddle pos) makeKeyboardEvent = do hSetBuffering stdin NoBuffering hSetBuffering stdout NoBuffering (buttonPressedSink, event) <- makeEvent =<< makeClock forkIO . forever $ getChar >>= buttonPressedSink return event main = do keyEvt <- makeKeyboardEvent let dirEvt = fmap key2dir keyEvt paddle = newPaddle (stepper PaddleStill dirEvt) 50 adaptE $ fmap print $ snapshot_ (paddleCenter paddle) $ atTimes [0, 0.01..] key2dir k = maybe PaddleStill snd $ find (($ k) . fst) [((== 'u'), PaddleUp), ((== 'd'), PaddleDown)] When I launch the program, I hit 'u' or 'd' and I see the position increase/decrease. If the beat ticks every second, I see the position being increased by 50 every second, which is normal, but it's a too low refresh rate for an app that is to run at 60fps. But when I set my beat to tick every 60 times per second, the position is well updated, but I clearly see that the display dramatically slows down after a few seconds of execution. Too heavy rate for integrate? That's why I'm asking: how should I use integrate?

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filterMP on keyboard-event taking 100% cpu
by Mathijs Kwik 11 Apr '10

11 Apr '10

Hi all, I decided to have another try with reactive and got the basics working. I created a simple program that just beeps until a timeout is reached or when a key gets pressed. This works OK, so I wanted to take it a small step further. Now, I only wanted to stop if the 'q' key is pressed (or timeout is reached). I tried filterE, filterMP and the alternative definition of filterMP found in the source. I found that in all cases, one thread of the program immediately grabs 100% cpu and makes the program sluggish/unresponsive. I'm on ghc 6.12.1 and compiled without any optimizations. here is my example: http://hpaste.org/fastcgi/hpaste.fcgi/view?id=24810 (everything works when "stopper" uses "keyevent" but breaks on "qevent¨) Is there anything I can do to get the behavior I want? Thanks, Mathijs

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Simple Tutorials ..
by Tom Poliquin 28 Feb '10

28 Feb '10

My student and I (sometimes it's difficult to determine who is who) have been struggling with understanding Reactive for several months and thanks to some initial help from this list (thanks Paul C) have been able to write three programs; two quite simple programs and one a bit more complex. Our purpose was twofold; to learn Reactive, and to create some simple tutorials so others might have an easier time. The programs and a brief tutorial are here, http://www.formicite.com/dopage.php?frp/frp.html We would appreciate any feedback. We might, in our euphoric naivete, have made errors, or at least been unorthodox in our API usage. It is our intent to publish one more program utilizing Reactive-FieldTrip. Tom and Tony P.S. We are running ghc 6.10.3 and reactive 0.11.4

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Time leak problem with integral
by Mitsutoshi Aoe 30 Jan '10

30 Jan '10

Hi folks, I've got stacked now because of a time leak problem with integral. The following program leaks CPU-time gradually: > import FRP.Reactive > import FRP.Reactive.LegacyAdapters > import Control.Applicative > type Velocity = Double > type Position = Double > data Car = Car { vel :: Velocity, pos :: Position } deriving Show > velocity :: Behavior Velocity > velocity = 1 > position :: Behavior Position > position = integral (atTimes [0, 0.5 ..]) velocity > car :: Behavior Car > car = Car <$> velocity <*> position > main :: IO () > main = adaptE $ print <$> car `snapshot_` atTimes [0, 0.5..] 1) why is the leak happen? 2) how can I fix this problem? Some more detailed informations: * reactive 0.11.4 * GHC 6.12.1 * Gentoo Linux (2.6.32-tuxonice, x86_64) * compiled with or without -O2 flag Thanks, -- Mitsutoshi Aoe

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