The first message I received about Axiom seemed to imply it was
released as non-free software by NAG, but now it looks like Axiom is
free software today. Sorry for the confusion.
If Axiom is released under the revised BSD license
then there is no difficulty linking it (in any sense)
with GPL-covered code.
Suppose I write a common lisp program like Axiom (licensed under
modified BSD). Suppose I use a GPLed Common Lisp and save a binary
image of the loaded program. If saving the image requires my common lisp
program to ALSO be GPLed then it is not possible to develop programs
using a GPLed Common Lisp.
This is a misunderstanding. Including a GPL-covered program in a
combination means the combination as a whole is covered by the GPL.
However, any individual piece can have a more permissive license,
such as for instance the revised BSD license.