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From: Tassilo Horn <tsdh@gnu.org>
To: Jean Louis <bugs@gnu.support>
Cc: emacs-tangents@gnu.org
Subject: Re: (*) -> 1
Date: Fri, 20 Jan 2023 14:02:43 +0100	[thread overview]
Message-ID: <87a62dl55j.fsf@gnu.org> (raw)
In-Reply-To: <Y8qNDKdApYyL/tuc@protected.localdomain>

Jean Louis <bugs@gnu.support> writes:

>> 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.
>
> For some reason PicoLisp is quite different than other Lisp. I have
> asked author about it.
>
> 15:09 <abu[m]> It is a "feature" that NIL propagates through
>                arithmetics

Well, but with (*) and (+), there is no single NIL involved!  And in
Elisp (+ nil), where actually a nil is involved, you get an error.

> 15:09 <jmarciano> How does it help instead of providing identity
>                   elements?
> 15:09 <abu[m]> (*) especially was not contemplated though, it is a
>                pretty useless call
> [...]
> 15:12 <abu[m]> What is a call like (*) useful for?
>
> As you see, author also asked naturally why is it useful.

So go and ask why he thinks (apply '+ ()) -> NIL is more useful than 0
given that the sum of the empty set of numbers _is_ 0.

>> So why does it return NIL?  And why do you apparently consider that
>> useful?  And can something be useful even though it is incorrect?
>
> I find it right as with error raising or nil I can find what is
> wrong.

It's good to signal an error when the expression is wrong as does Elisp
with

  (+ nil)
  (* 1 2 nil)
  (apply #'+ (list 1 nil 19))
  (+ 2 "i am not a number")

but when there is no nil or otherwise wrongly typed value involved,
there's nothing to signal.

Bye,
Tassilo



  reply	other threads:[~2023-01-20 13:02 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <Y8Y2JgamG+C2VxFw@protected.localdomain>
     [not found] ` <87y1q1kvdm.fsf@web.de>
     [not found]   ` <Y8bM7K8T9uMHdSRw@protected.localdomain>
     [not found]     ` <87h6wpkrlq.fsf@web.de>
     [not found]       ` <Y8bjItPWgBLLdR9s@protected.localdomain>
     [not found]         ` <87zgahj7h3.fsf@web.de>
     [not found]           ` <Y8fly8k72s+iVJYF@protected.localdomain>
     [not found]             ` <878rhzvs1h.fsf@web.de>
     [not found]               ` <Y8kAkHzCnCS35D8v@protected.localdomain>
     [not found]                 ` <87ilh28w9u.fsf@web.de>
2023-01-19 14:54                   ` (*) -> 1 Jean Louis
     [not found]                   ` <Y8lZmM1EQ+wShgt2@protected.localdomain>
     [not found]                     ` <87r0vqa67k.fsf@gnu.org>
2023-01-20  7:05                       ` Jean Louis
2023-01-20  8:52                         ` Tassilo Horn
2023-01-20 12:46                           ` Jean Louis
2023-01-20 13:02                             ` Tassilo Horn [this message]
2023-01-20 16:06                               ` Jean Louis
2023-01-21  8:19                                 ` Tassilo Horn
2023-01-22  4:30                                   ` Emanuel Berg
2023-01-22  6:55                                     ` Jean Louis
2023-01-22 10:56                                       ` Emanuel Berg
2023-01-23  3:40                                         ` [External] : " Drew Adams
2023-01-22 14:34                                     ` Akib Azmain Turja
2023-01-23  2:23                                       ` Emanuel Berg
2023-01-23  5:37                                       ` Jean Louis
2023-01-23  5:55                                       ` Jean Louis
2023-01-24  2:33                                         ` Emanuel Berg
     [not found]                   ` <SJ0PR10MB5488B34F22BFC45644C9C647F3C49@SJ0PR10MB5488.namprd10.prod.outlook.com>
2023-01-20  7:33                     ` [External] : " Jean Louis
     [not found] <87bkmxkpzg.fsf@web.de>
     [not found] ` <878ri1av5j.fsf@telefonica.net>
     [not found]   ` <87ilh4kgqo.fsf@web.de>
     [not found]     ` <87zgagakh5.fsf@telefonica.net>
     [not found]       ` <87cz7cka06.fsf@web.de>
     [not found]         ` <87v8l49t8w.fsf@telefonica.net>
     [not found]           ` <Y8evxjuR1YQWW10L@tuxteam.de>
     [not found]             ` <87h6wo9fjb.fsf@telefonica.net>
     [not found]               ` <87edrsufdd.fsf@web.de>
     [not found]                 ` <878ri09bsh.fsf@telefonica.net>
2023-01-19  8:37                   ` Jean Louis

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