Bug report ID:635627 - subst([...] is order-dependent

On Thu, Apr 1, 2010 at 2:32 PM, Dieter Kaiser <drdieterkaiser at web.de> wrote:

> When I summarize the different opinions I think it is the best not to
> change the current implementation of subst, to add some documentation
> about the way substitute works, and to close the open bug report as
> "won't fix".

OK.

> Adding a function like psubstitute for parallel substitution which has a
> functionality comparable to the function substitute.

OK by me, but let's call it psubst to make it similar to the existing function.

> Adding a flag to the existing function substitute to switch on parallel
> substitution.

Opposed.

> Remark: I think it is not a good idea to try to extend sublis to get a
> functionality like substitute, because we have to double a lot of code.

If we invent psubst to be like parallel version of subst,
can we get rid of sublis ? (Or get sublis to punt to psubst?)
I don't like functions which differ in subtle ways.

Aside from the serial versus parallel difference which we are
going to make explicit, there is also the question of how
simplification occurs; that's really a mess. Sorry, I don't know
how to clean it up.

best

Robert Dodier