> I did not specify that there is only one bridge, nor that you finish > processing a message from a bridge before we start processing another next. > If you model the island as a single actor, you would fail to represent many > of the non-deterministic interactions possible in the 'island as a set' of > actors.
Ok, I think I see the distinction you're painting here from a meta perspective of reasoning about an actor system. I keep on jumping back in into the message-only perspective, where the difference is (it seems) unknowable. But with meta reasoning about the system, which is what I think you've been trying to get me to see, the difference matters and complicates reasoning about the thing as a whole. I cannot fathom your optimism. I think it's more of a pessimism about other models that leads me to be non-pessimistic about actors :D. I have some specific goals I want to achieve with computation, and actors are the only things right now that seem to fit. What we can say of a model is often specific to how we implemented it, the > main exceptions being compositional properties (which are trivially a > superset of invariants). Ad-hoc reasoning easily grows intractable and > ambiguous to the extent the number of possibilities increases or depends on > deep implementation details. And actors model seems to go out of its way to > make reasoning difficult - pervasive state, pervasive non-determinism, > negligible ability to make consistent observations or decisions involving > the states of two or more actors. > I think any goal to lower those comprehension barriers will lead to > development of a new models. Of course, they might first resolve as > frameworks or design patterns that get used pervasively (~ global > transformation done by hand, ugh). Before RDP, there were reactive design > patterns I had developed in the actors model while pursuing greater > consistency and resilience. I think we're back to different reference points, and different goals. What follows is not a comment on what you said but my attempt to communicate why I'm going about it the way I am and continue to resist what I'm sure are sound software meta-reasoning practices. My non-pessimism about actors is linked to Wolfram's cellular automata turing machine ( http://blog.wolfram.com/2007/10/24/the-prize-is-won-the-simplest-universal-turing-machine-is-proved/). My continuing non-pessimism about interesting computation being possible in actors is his search for "our universe" ( http://blog.wolfram.com/2007/09/11/my-hobby-hunting-for-our-universe/). Cellular automata are not actors, I get that, but these to me are the hints. Another hint is the structure of HTMs and the algorithm reverse engineered from the human neocortex ( https://www.numenta.com/htm-overview/education/HTM_CorticalLearningAlgorithms.pdf). Another hint are what we call mesh networks. And overwhelming consideration across all those hints is unbounded scalability. Cheers, Tristan On Tue, Apr 9, 2013 at 6:25 PM, David Barbour <[email protected]> wrote: > On Tue, Apr 9, 2013 at 12:44 PM, Tristan Slominski < > [email protected]> wrote: > >> popular implementations (like Akka, for example) give up things such as >> Object Capability for nothing.. it's depressing. >> > > Indeed. Though, frameworks shouldn't rail too much against their hosts. > > >> >> I still prefer to model them as in every message is delivered. It wasn't >> I who challenged this original guaranteed-delivery condition but Carl >> Hewitt himself. >> > > It is guaranteed in the original formalism, and even Hewitt can't change > that. But you can model loss of messages (e.g. by explicitly modeling a > lossy network). > > >> You've described composing actors into actor configurations :D, from the >> outside world, your island looks like a single actor. >> > > I did not specify that there is only one bridge, nor that you finish > processing a message from a bridge before we start processing another next. > If you model the island as a single actor, you would fail to represent many > of the non-deterministic interactions possible in the 'island as a set' of > actors. > > >> I don't think we have created enough tooling or understanding to fully >> grok the consequences of the actor model yet. Where's our math for emergent >> properties and swarm dynamics of actor systems? [..] Where is our reasoning >> about symbiotic autopoietic and allopoietic systems? This is, in my view, >> where the actor systems will shine > > > I cannot fathom your optimism. > > What we can say of a model is often specific to how we implemented it, the > main exceptions being compositional properties (which are trivially a > superset of invariants). Ad-hoc reasoning easily grows intractable and > ambiguous to the extent the number of possibilities increases or depends on > deep implementation details. And actors model seems to go out of its way to > make reasoning difficult - pervasive state, pervasive non-determinism, > negligible ability to make consistent observations or decisions involving > the states of two or more actors. > > I think any goal to lower those comprehension barriers will lead to > development of a new models. Of course, they might first resolve as > frameworks or design patterns that get used pervasively (~ global > transformation done by hand, ugh). Before RDP, there were reactive design > patterns I had developed in the actors model while pursuing greater > consistency and resilience. > > Regards, > > Dave > > > _______________________________________________ > fonc mailing list > [email protected] > http://vpri.org/mailman/listinfo/fonc > >
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