[racket] Does Redex have support for multi-hole evaluation contexts?

From: Robby Findler (robby at eecs.northwestern.edu)
Date: Sat Jul 7 23:04:18 EDT 2012

No, there is no way to do that in Redex.

Are you trying to model parallelism?


On Sat, Jul 7, 2012 at 9:29 PM, Lindsey Kuper <lkuper at cs.indiana.edu> wrote:
> Hi,
> I have a Redex model for a language witih an explicitly parallel
> reduction semantics, where an application (e1 e2) can step to (e1'
> e2') -- that is, where both the operator and the operand can step at
> once.  Because we wanted to explicitly model this parallel reduction,
> we first thought of using multi-hole evaluation contexts, but a
> mailing list thread that I found from 2009
> (http://lists.racket-lang.org/users/archive/2009-October/036237.html)
> indicated that Redex didn't support those (in fact, that person was
> trying to solve a similar problem).
> So, instead, we use an inference-rule-based semantics (defined using
> `define-judgment-form`, with the reduction relation defined as a thin
> wrapper around `judgment-holds`, something like in
> http://git.racket-lang.org/plt/blob/HEAD:/collects/redex/examples/define-judgment-form/sos.rkt).
>  This has been working fine, but I'm curious if it's still necessary
> to do it that way, or if Redex now supports multi-hole contexts -- or
> if there is yet another way to do explicit parallel reductions that
> I've not yet considered.
> Thanks,
> Lindsey
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