Re: [Maxima-discuss] reworking printf, was: maxima: printf hangs with format string, works in lisp mode

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

How do I use "~m"?
Here's what I tried (on a very recent SBCL Maxima):

  format([args]) := apply(?format, append([false], args));
  o : a^"b";
  format("~a", o);   /* ((MEXPT SIMP) $A b) */
  format("~s", o);   /* ((MEXPT SIMP) $A "b") */
  format("~m", o);   /* Unknown format directive */

Thanks in advance!
  Eduardo


On Sat, 17 May 2025 at 16:32, Robert Dodier <rob...@gm...> wrote:

> Maxima's printf has a lot of great things going for it, mostly
> inherited from Common Lisp FORMAT.
>
> As wonderful as it is, FORMAT doesn't provide a way to define new
> format directives or redefine existing ones. At present the
> Maxima-specific directives (~h for bigfloat, ~m for 2-d pretty printer
> output) and redefined directives (~a and ~s for 1-d output) are
> implemented by effectively reimplementing some large part of FORMAT,
> in particular the stuff for looping.
>
> I have wondered about how to handle printf in a neater way, mostly
> with the goal of fixing bugs, although it's not out of the question to
> make it simpler to define or redefine additional directives.
>
> I wonder if it's thinkable to start with an existing FORMAT
> implementation and then bolt on the Maxima-specific bits. I haven't
> investigated. Or we could take a second look at the existing printf
> code and see if the looping stuff could be revised.
>
> At this point I'm interested to hear comments about this stuff at a
> high level -- we can work out details if we can arrive at a workable
> plan.
>
> FWIW & all the best.
>
> Robert
>
>