Re: [Maxima-discuss] Idiomatic way to add a SIMP when needed?

[Robert D. <rob...@gm...>]

On Fri, Oct 3, 2025 at 9:41 PM Eduardo Ochs <edu...@gm...> wrote:

> Now the real question. I would like to try to replace the Lisptree
> functions that traverse Maxima objects/trees by other functions that
> don't simplify subobjects/subtrees, and I am looking for _idiomatic_
> ways to do that in Lisp.

I gather from the example that you gave, and looking at the
implementation of Lisptree (https://anggtwu.net/lisptree.html), the
problem is that Maxima is simplifying function call results in the
Maxima code, lisptree.mac. I can think of a couple of ways to avoid
that.

One is to rewrite lisptree.mac in Lisp, so that the Maxima simplifier
isn't called. I see that lisptree.mac is fairly extensive, so maybe
that's easier said than done.

The other is to disable the simplifier when you're extracting bits of
expressions, e.g. block([simp: false], [myop, myargs]: [op (expr),
args (expr)], ...). If you are only taking expressions apart, and not
putting them together, there should be fewer surprising consequences
of disabling the simplifier.

> The real question is: does Maxima have an
> utility function that receives a Maxima object and returns a version
> of it "with a simp added if needed"?

This is generally an approach that leads to ongoing headaches, since
many functions will make assumptions about what they're working with
if they see the SIMP flag. I don't usually say stuff like this but in
this case -- my advice is just don't do that. FWIW.

All the best,

Robert