.... we have nothing to gain by
> copying Mathematica.
in the absence of a better idea, I think that copying mathematica IS a good
idea because it can benefit people who want to move programs from one to the
other, or who want to read programs in one or the other system.
Also, some smart people worked on Mathematica. Maybe they did it right..
I'd prefer generally to copy from Common Lisp, which was designed by very
smart people working in an open standard environment. But Common Lisp
primitive functions are not aimed at symbolic math, so may not offer the
extension ideas.
RJF