Hi Tony
Yes, I've seen it. As Gerry says, it is an extension of Guy Steele's thesis.
When I read this, I wished for a more interesting, comprehensive and
wider-ranging and -scaling example to help think with.
One reason to put up with some of the problems of defining things using
constraints is that if you can organize things well enough, you get super
clarity and simplicity and power.
They definitely need a driving example that has these traits. There is a
certain tinge of the Turing Tarpit to this paper.
With regard to objects, my current prejudice is that "objects should be able to
receive messages, but should not have to send to explicit receivers". This is a
kind of multi-cast I guess (but I think of it more like publish/subscribe).
Cheers,
Alan
>________________________________
> From: Tony Garnock-Jones <[email protected]>
>To: Alan Kay <[email protected]>; Fundamentals of New Computing
><[email protected]>
>Sent: Monday, February 27, 2012 9:48 AM
>Subject: Re: [fonc] Error trying to compile COLA
>
>
>Hi Alan,
>
>
>On 27 February 2012 11:32, Alan Kay <[email protected]> wrote:
>
>[...] a better constraint system. [...] This has led us to start putting
>constraint engines into STEPS, thinking about how to automatically organize
>various solvers, what kinds of POLs would be nice to make constraint systems
>with, UIs for same, and so forth.
>
>Have you looked into the "Propagators" of Radul and Sussman? For example,
>http://dspace.mit.edu/handle/1721.1/44215. His approach is closely related to
>dataflow, with a lattice defined at each node in the graph for integrating the
>messages that are sent to it. He's built FRP systems, type checkers, type
>inferencers, abstract interpretation systems and lots of other fun things in a
>nice, simple way, out of this core construct that he's placed near the heart
>of his language's semantics.
>
>My interest in it came out of thinking about integrating pub/sub (multi- and
>broadcast) messaging into the heart of a language. What would a Smalltalk look
>like if, instead of a strict unicast model with multi- and broadcast
>constructed atop (via Observer/Observable), it had a messaging model capable
>of natively expressing unicast, anycast, multicast, and broadcast patterns?
>Objects would be able to collaborate on responding to requests... anycast
>could be used to provide contextual responses to requests... concurrency would
>be smoothly integrable... more research to be done :-)
>
>Regards,
> Tony
>--
>Tony Garnock-Jones
>[email protected]
>http://homepages.kcbbs.gen.nz/tonyg/
>
>
>
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