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From: Daniel Cerqueira <dan.list@lispclub.com>
Newsgroups: comp.lang.lisp
Subject: Re: Undefined in LISP
Date: Sun, 23 Mar 2025 16:56:35 +0000
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Lawrence D'Oliveiro <ldo@nz.invalid> writes:

> On Sat, 22 Mar 2025 12:07:14 +0000, Daniel Cerqueira wrote:
>
>> Lawrence D'Oliveiro <ldo@nz.invalid> writes:
>> 
>>> On Fri, 21 Mar 2025 22:47:38 +0000, Daniel Cerqueira wrote:
>>>
>>>> I would like to know your thoughts, about what being undefined
>>>> actually is. Should an undefined expression be represented by a
>>>> symbol, or should an undefined expression be silent (without
>>>> returning a symbol)?
>>>
>>> Should an attempt to evaluate such an expression even terminate?
>> 
>> My opinion is that it should...
>
> So undefined behaviour cannot be really undefined, it must return some 
> kind of value we are going to arbitrarily name as “undefined”?

Does every LISP S-expression need to have a value (need to be
evaluated)?  Is atributing a symbol to undefined behaviour needed?

-- 
The pioneers of a warless world are the youth that
refuse military service. ~ Albert Einstein