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

[Yuri Khan]

On Mon, 16 Jan 2023 at 17:17, Jean Louis <bugs@gnu.support> wrote:

> By above I do not see reference to Lisp. What you state above is not
> what Lisp function is supposed to do and it does not tell why is it
> so in Lisp, do you know?

In mathematics the sum of zero elements is zero and the product of
zero elements is one. In Lisp the + function implements the
mathematical sum, and * the product. Lisp chooses to allow more than
two arguments for the sum and product, so why would it impose any
artificial restriction on less than one?

> > + is a built-in function in ‘C source code’.
> > (+ &rest NUMBERS-OR-MARKERS)
> > Return sum of any number of arguments, which are numbers or markers.

What it doesn’t say explicitly is that any markers are implicitly
converted to numbers. After that, all arguments (if any) are numbers,
and can be dealt with according to number rules.