Re: [Haskell-cafe] Tetris

Conal Elliott wrote:

On Nov 21, 2007 3:49 AM, Laurent Deniau mailto:laurent.deniau@cern.ch> wrote:

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Peter Verswyvelen wrote:

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Conal Elliott wrote:

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Moreover, functional programming makes it easy to have much more state than imperative programming, namely state over *continuous* time. The temporally discrete time imposed by the imperative model is pretty puny in comparison. Continuous (or "resolution-independent") time has the same advantages as continuous space: resource-adaptive, scalable, transformable. Yes, that's true, but isn't that also the problem with FRP? I mean, most of the papers I'm reading about (A)FRP indicate that no matter how nice it is to have the continuous time model

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I agree with Conal, it's not a continuous time model but a resolution-independent time model.

What do mean by resolution-independent vs continuous?

I mean time may or may not be part or the model in FRP.

I meant them more-or-less synonymously. Semantically, there's no notion of resolution. When it's time to introduce a resolution for discrete rendering, there's no resolution imposed by the model.

Right. This is why I do not see the relation with the number of bits in a float. Time could be represented by states, in the sens of a state machine with asynchronous events.

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The reason it that Arrows (like Monads) encapsulate the sequence of transitions. Unless the time is a parameter of the transition, it is independent of the time (resolution), but still captures its ordered nature.

I'm confused again. I don't think of Arrow as implying transitions at all.

I call a transition the operator >>= for Monad, and arr for Arrow. I was maybe not clear in this point. The correct wording might be a computation.

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to get fine grained control over execution times and resources, one needs to fall back to the discrete delta-time approach?

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If you need synchronization, yes.

Why? What about synchronization implies discretness in the model?

Because it requires either specific states which are aware of each other (asynchronous events), or a known delta-time. How do you synchronize continuous events (I would says more continuous processes) ? Regards, ld.