RE: [External] : Re: How to make M-x TAB not work on (interactive) declaration?

[Drew Adams]

> Return sum of any number of arguments, which are numbers or markers.
> 
> Thus sum of any number of no arguments cannot be zero,
> because there were no arguments.

Not to belabor this... but perhaps you're missing
understanding _zero as a number_, in "number of
arguments".  More precisely: zero or more args.

"Sum" can be defined in various ways, and yes, if
it's defined to accept _any number of args_ then
it's kosher, as one possibility, for "any number"
to include the fine, upstanding number that is zero.

> Description says:
> (* &rest NUMBERS-OR-MARKERS)
> Return product of any number of arguments, which are
> numbers or markers.
> 
> Product of no arguments cannot be possibly zero, so

Yes, it can.  And typically it is.  See sum, above.

Zero was apparently first considered a full-fledged
number in the 7th century, in India.  Europe didn't
catch on till the 12th century.  Before that, at
most it was a bookkeeping _placeholder_ for an
absence/nothing.

> I do understand that there is some LISP mystery
> why is it so.

This has nothing per se to do with Lisp.  And there's
really no mystery.