[Stackless] Re: Stackless Python Logic Variables?

David Hopwood david.hopwood at zetnet.co.uk
Wed Jun 11 03:26:18 CEST 2003


[cross-posted to <e-lang at mail.eros-os.org> from the Mozart/Oz list]

Denys Duchier wrote:
> jabowery at technicalpursuit.com (James A. Bowery) writes:
> >> >     Stackless Python [1] is an ideal environment within which to
> >> >     implement logic variables for thread synchroniziation [2].
> >> >     The 3 additions required for this are 1) the addition of the
> >> >     "unknown" keyword that declares a logic variable, 2) the
> >> >     "final" keyword that declares a logic variable to be single-
> >> >     assignment and 3) the "=:=" operator that performs a
> >> >     unification of a logic variable with an expression.
> I don't think that would be the way to do it.  This just doesn't fit
> the Python way.
>     Q. What is the expected benefit?
>     A. Transparent synchronization on data.
> In this regard, the better generalization (which for us was started in
> Mozart and pursued in Alice) is the dual notion of future/promise and
> does not apeal to the notion of logic variable nor of unification.

For an example of a language that supports dataflow variables/promises
without unification, see E (www.erights.org; I suggest starting with
<http://www.erights.org/elang/intro/quickE.html>). I agree that this
approach may be better suited for an extension to Python.

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David Hopwood <david.hopwood at zetnet.co.uk>

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