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

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

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