[reactive] Re: An adapter for SDL

My test program leaks memory as it runs and does not react to clicks,

Sorry, I meant keyboard presses. Facundo 2010/8/5 Facundo Domínguez :

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@(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