[Haskell-cafe] [reactive] A pong and integrate

[Limestraël]

Why isn't it possible to make a Pong with Reactive? Where is the problem?
Conceptually, I don't see where it is. IMO, it's a time-leak issue due to a
Reactive bug, but it is not a limitation of Reactive.
I mean, it's not that it *can't* work, it's that it *should* work, shouldn't
it?

And why would it be more possible with Yampa?
I've already checked Yampa, but I find it much less simple and easy to use
than Reactive.
Moreover, I tried the space invaders sample (the sample that the paper
"Yampa Arcade" is about), and it lauches but it is completely unusable (I do
have a decent PC, and I get like 5fps and a gun which absolutely doesn't
move correctly). Not very appealing ^^, but maybe the problem is with the
code of the game itself or with my PC, not with Yampa...

I did not look thoroughly at elerea, but at least, when I tried its sample
"dungeons of wor" it worked properly ;)
I will have a look...

2010/5/16 Peter Verswyvelen <bugfact at gmail.com>

> As far as I know, it was never possible to make a pong game in
> Reactive, at least not with the versions I tried, but I admit a lot of
> never versions got released since then. It would be great to see one
> though :)
>
> You might want to try Yampa, that works for sure (although you should
> mark all your output data strict, as is done in the examples,
> otherwise you might also get space leaks or shaky frame rates). Or
> Elerea, which comes with a breakout game.
>
> On Sun, May 16, 2010 at 9:30 PM, Limestraël <limestrael at gmail.com> wrote:
> > Eventually, I don't think it is a profiling issue.
> > Maybe a problem with integral. According to a quite recent post on the
> > reactive mailing list, the following minimal code produces the same
> problem
> > :
> >
> >> 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) or Ubuntu 9.10 64bits
> >> * compiled with or without -O2 flag
> >
> > 2010/5/16 David Leimbach <leimy2k at gmail.com>
> >>
> >>
> >> On Sat, May 15, 2010 at 8:42 AM, Limestraël <limestrael at gmail.com>
> wrote:
> >>>
> >>> Okay,
> >>> guess I'll have to bring out the chapter 25 of my Real World Haskell...
> >>
> >> I find it's often the most practical chapter that I hit a lot during
> >> writes and changes to my server process I have in Haskell in our control
> >> system code :-)
> >> That plus the information that I had missed that Control.Monad.State
> >> defaulted to the Lazy version (which is consistent, but for some reason
> it
> >> got by me) helped me to realize why I was leaking so much space in a
> garbage
> >> collected environment.
> >> I wouldn't have gotten very far with Haskell as this piece of our code
> >> without that chapter.  I'd love to see more writing of that sort around
> >> Haskell in book form.  One can become fluent in tuning Haskell by trial
> and
> >> error, but the sharp corners one must bump into are often sharper than
> in
> >> other languages I've found.
> >> Dave
> >>
> >>>
> >>> 2010/5/15 Bulat Ziganshin <bulat.ziganshin at gmail.com>
> >>>>
> >>>> Hello Limestraėl,
> >>>>
> >>>> Saturday, May 15, 2010, 7:02:38 PM, you wrote:
> >>>>
> >>>> > 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?
> >>>>
> >>>> it may be due to lot of uncollected garbage that is result of lazy
> >>>> evaluation. profile program to check its GC times
> >>>>
> >>>>
> >>>> --
> >>>> Best regards,
> >>>>  Bulat                            mailto:Bulat.Ziganshin at gmail.com
> >>>>
> >>>
> >>>
> >>> _______________________________________________
> >>> Haskell-Cafe mailing list
> >>> Haskell-Cafe at haskell.org
> >>> http://www.haskell.org/mailman/listinfo/haskell-cafe
> >>>
> >>
> >
> >
> > _______________________________________________
> > Haskell-Cafe mailing list
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> >
> >
>
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