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Re: (*) -> 1


From: Tassilo Horn
Subject: Re: (*) -> 1
Date: Fri, 20 Jan 2023 09:52:16 +0100
User-agent: mu4e 1.9.16; emacs 30.0.50

Jean Louis <bugs@gnu.support> writes:

>> Gosh, Jean, of course nobody would literally write (*) but (apply #'*
>> ...), and you'll find occurrences in emacs:
>
> That has been said that is not necessarily problem or reason. 

I don't understand that sentence.

> Did you see reference to PicoLisp?

Yes, and I think it's seriously wrong with

  : (+)
  -> NIL

where its docs say

  Returns the sum of all num arguments. When one of the arguments
  evaluates to NIL, it is returned immediately.

Well, in (+) there exists no argument evaluating to NIL and
mathematically, the sum of zero numbers is 0
(https://en.wikipedia.org/wiki/Empty_sum).  Same for the empty product
(*) which should be 1 (https://en.wikipedia.org/wiki/Empty_sum) but also
gives NIL in picolisp.

So why does it return NIL?  And why do you apparently consider that
useful?  And can something be useful even though it is incorrect?

Bye,
Tassilo



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