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

[Eduardo O. <edu...@gm...>]

Hi list,

my "Lisptree" thing - see
<https://anggtwu.net/eev-maxima.html#lisptree> - has several parts
that were written in a very naive way, and that I am trying to
rewrite... in particular, I tried to see if Lisptree would handle
"superquoted" objects correctly - see:

https://github.com/maxima-project-on-github/maxima-packages
https://github.com/maxima-project-on-github/maxima-packages/tree/master/robert-dodier/superq

and it turns out that it doesn't. Here's an example that shows that
Lisptree simplifies a ((MFACTORIAL) 5) to 120:

  (%i20) o1 : superq(n!);
  (%o20)                            superq(n!)
  (%i21) o2 : superq(5!);
  (%o21)                            superq(5!)
  (%i22) format0(o1);
  (%o22)                   (($SUPERQ) ((MFACTORIAL) $N))
  (%i23) format0(o2);
  (%o23)                   (($SUPERQ) ((MFACTORIAL) 5))
  (%i24) lisptree(o1);
  (%o24)
  superq
  |
  !
  |
  n
  (%i25) lisptree(o2);
  (%o25)
  superq
  |
  120
  (%i26)

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. 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"? I'm thinking on something that
would work like this:

  (addsimp '((mfactorial) 5))
  ;; ->    '((mfactorial simp) 5))
  (addsimp '((mfactorial simp) 5))
  ;; ->    '((mfactorial simp) 5))
  (addsimp 42)
  ;; ->    42
  (addsimp "foo")
  ;; ->    "foo"

and that would be better than this quick-and-dirty hack...

  (defun addsimp-inner (flags)
    (if (member 'simp flags) flags (cons 'simp flags)))

  (defun addsimp (o)
    (if (consp o)
        `((,(caar o) ,@(addsimp-inner (cdar o))) ,@(cdr o))
        o))

Thanks in advance!
  Eduardo