Erlang style processes for Python

[Kay Schluehr]

Every once in a while Erlang style [1] message passing concurrency [2]
is discussed for Python which does not only imply Stackless tasklets
[3] but also some process isolation semantics that lets the runtime
easily distribute tasklets ( or logical 'processes' ) across physical
processes. Syntactically a tasklet might grow out of a generator by
reusing the yield keyword for sending messages:

yield_expr : 'yield' ([testlist] | testlist 'to' testlist)

where the second form is specific for tasklets ( one could also use  a
new keyword like "emit" if this becomes confusing - the semantics is
quite different ) and the addition of a new keyword for assigning the
"mailbox" e.g:

required_stmt: 'required' ':' suite

So tasklets could be identified on a lexical level ( just like
generators today ) and compiled accordingly. I just wonder about
sharing semantics. Would copy-on-read / copy-on-write and new opcodes
be needed? What would happen when sharing isn't dropped at all but
when the runtime moves a tasklet around into another OS level thread /
process it will be pickled and just separated on need? I think it
would be cleaner to separate it completely but what are the costs?

What do you think?

[1] http://en.wikipedia.org/wiki/Erlang_programming_language
[2] http://en.wikipedia.org/wiki/Actor_model
[3] http://www.stackless.com/