Re: [Haskell-cafe] Re: A few ideas about FRP and arbitrary access in time
On Tue, Mar 09, 2010 at 05:23:56AM +, Aaron Denney wrote: On 2010-03-08, Brandon S. Allbery KF8NH allb...@ece.cmu.edu wrote: There is a discrete time quantum. But unless you're doing simulations at the quantum level, you really don't want to go there (even ignoring that one second of real time would take a really long time to calculate on current hardware :); stick to macrocosmic physics, which is statistically continuous. That's ... contentious. In both quantum mechanics and GR, time is completely, flattly, continuous. In certain extremely speculative frameworks attempting to combine the regimes in which they are applicable, that may not be the case. But for accepted physics models, time really is continous. Hmm.. I thought something interesting happened on the scale of the plank time, 10^-44 seconds or so. Or is that only relevant to our ability to _measure_ things at that scale and not the continuity of time itself as far as QM is concerned? John -- John Meacham - ⑆repetae.net⑆john⑈ - http://notanumber.net/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: A few ideas about FRP and arbitrary access in time
On Mar 9, 2010, at 9:34 AM, John Meacham wrote: Hmm.. I thought something interesting happened on the scale of the plank time, 10^-44 seconds or so. Or is that only relevant to our ability to _measure_ things at that scale and not the continuity of time itself as far as QM is concerned? Quantum mechanics itself does not have a natural time scale at which interesting things start to happen, but some theories built using quantum mechanics do. It helps if you think of quantum mechanics as being like Newton's laws: it is not a theory itself so much as a metatheory that provides ground rules for how to construct theories of nature. (And yes, I actually am a quantum physicist. :-) ) Cheers, Greg ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: A few ideas about FRP and arbitrary access in time
On Sun, Mar 7, 2010 at 10:01 AM, sinelaw jones.noa...@gmail.com wrote: I don't think a deep knowledge of physics is what we lack here, at least for the question of continuous vs. discrete time. Maybe the best physical model for nature really does involve discrete time steps. However, for our everyday experiences (and maybe for anything that's not on a the tiny quantum scale?) continuous time is the most natural model to follow. And when modeling changing values such as mouse position (the perpetual example...), animations, sound, etc. continuous time seems much more natural. Don't forget to check out the link Conal posted, his short blog post about the subject: http://conal.net/blog/posts/why-program-with-continuous-time/ Sure, using continuous time sounds obvious, but the principle What Would Reality Do feels scary, because we really don't know what Reality is when it comes to time; or anything really, all we have is mathematical models that work good enough, and sometimes we have two different models that are used depending on how we want approach a certain problem (e.g. light: wave versus particle) I'm a game developer and I don't care to much about reality. But when I'm not in hacking mode to Get Things Done, I do care about composable, maintainable, and beautiful pieces software, and the way games are developed today are IMO far from that, so hopefully FRP will solve this one day and be efficient enough to run on average hardware. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: A few ideas about FRP and arbitrary access in time
On Mar 7, 2010, at 04:01 , sinelaw wrote: I don't think a deep knowledge of physics is what we lack here, at least for the question of continuous vs. discrete time. Maybe the best There is a discrete time quantum. But unless you're doing simulations at the quantum level, you really don't want to go there (even ignoring that one second of real time would take a really long time to calculate on current hardware :); stick to macrocosmic physics, which is statistically continuous. -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon universityKF8NH PGP.sig Description: This is a digitally signed message part ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: A few ideas about FRP and arbitrary access in time
On Wed, Mar 3, 2010 at 8:45 PM, sinelaw jones.noa...@gmail.com wrote: But isn't Lucid Synchrone essentially discrete-timed? Also, events Maybe reality itself can also be modeled using discrete timesteps? If so, then a discrete clock calculus might make a lot of sense. I don't know much about theoretical physics - I think general relativity still is the best model for time, and it's continuous in that model - but maybe the people with a PhD in physics know more about it :-) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: A few ideas about FRP and arbitrary access in time
Kind of a long shot, from what I can make out, but Timber might be interesting - Haskell-like programming language with a reactive model that supports time as a sort of event. http://www.timber-lang.org/ Certainly not much like what we're talking about, but I haven't picked up on the application domain of `behaviors' - for all I know that's just about working around the lack of support for time events. Donn ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: A few ideas about FRP and arbitrary access in time
Even if the implementation is discrete (as all digital hardware), it may be more natural to treat things such as a temperature sensor, mouse position, and perhaps even video as functions of continuous time, values that vary continuously. So behaviors are not a workaround at all, in this sense. Just as we program with infinite lists etc even though the implementation is finite. In this way, implementations serve abstractions/semantics/specifications, rather than vice versa. See also http://conal.net/blog/posts/why-program-with-continuous-time/ . - Conal ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
