laurent.deniau at cern.ch
Fri Nov 23 03:09:53 EST 2007
Conal Elliott wrote:
> On Nov 21, 2007 3:49 AM, Laurent Deniau <laurent.deniau at cern.ch
> <mailto:laurent.deniau at cern.ch>> wrote:
> > Peter Verswyvelen wrote:
> > > Conal Elliott wrote:
> > >> Moreover, functional programming makes it easy to have much more
> > >> 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
> > >> 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,
> > > of the papers I'm reading about (A)FRP indicate that no matter how
> > > it is to have the continuous time model
> > 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.
> > 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.
> > > to get fine grained control
> > > over execution times and resources, one needs to fall back to the
> > > discrete delta-time approach?
> > 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) ?
More information about the Haskell-Cafe