using common lisp packages to avoid re-definitions/ powerset

This is what the common lisp package system is
intended to handle. I personally find it very
difficult to use, but maybe that's because I never
figured out how to get things to compile right in
ANSI CL and also in the lower-case preferred version
of Allegro CL.
   Macsyma tried to do some separation into internal
and external programs back in the 1960's with
the $ command name prefix. Also you might see some
code in declarations with "genprefix"  but this had
to do with keeping labels generated by a compiler from
colliding.
RJF