reading carl hewitt's seminal paper on the actor model:
http://www.lcs.mit.edu/publications/specpub.php?id=762
my current impression is that actors are basically pure-OO objects
using continuations (coroutines?) instead of stack-frame
methods/subroutines.  this way objects only require "promises" (in the
form of the passing of context) rather than the final value (as with
method stack-frames).  (i think this important towards breaking free
from von neumann architecture, ala bachus:
http://delivery.acm.org/10.1145/360000/359579/p613-backus.pdf?key1=359579&key2=7975779801&coll=portal&dl=ACM&CFID=11111111&CFTOKEN=2222222

but i still can't quite seem to grok continuations, at least in terms
of interpreting it for ruby, w/r/t closures and Kernel#callcc.  this
after reading dan "parrot" sugalski's weblog
[http://www.sidhe.org/~dan/blog/], jim weirich's email
[http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/78288
], and rubygarden/c2.com/wikipedia articles on the subject:
http://www.rubygarden.org/ruby?action=history&id=Continuations
http://rubygarden.org/ruby?ContinuationExplanation
http://www.ruby-doc.org/docs/ProgrammingRuby/html/ref_c_continuation.html
http://c2.com/cgi/wiki?ContinuationExplanation
http://en.wikipedia.org/wiki/Subroutine
http://en.wikipedia.org/wiki/Coroutine


any futher help is much appreciated.

thanks!

-z