laurent.deniau at cern.ch
Wed Nov 21 06:49:48 EST 2007
Peter Verswyvelen wrote:
> Conal Elliott wrote:
>> 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,
> 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
I agree with Conal, it's not a continuous time model but a
resolution-independent time model. 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.
> 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.
> And you still need to think about where
> you have to introduce delays to avoid infinite loops?
I don't see why, unless you want to have a memory or explicitly stop the
time which means it's a parameter of the transition as mention above
(but instantaneous transitions seems strange). So, the causality of the
transitions with a discrete time should not lead to infinite loops. The
time delay exists de facto.
> Since nobody replied yet on my question about the future of (A)FRP,
> maybe I can ask it again here? What is the future for FRP? Are other
> approaches better suitable for reactive applications?
I missed your question, but it's an interesting question. I found very
interesting and instructive the paper of Hai Liu and Paul Hudak on the
problem of space leaks in FRP.
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