Russ Allbery wrote:
> I agree with Tom; I think it's pretty self-evident that they're the same
> thing. undef means exactly the same thing as null; that's not the
> problem. The problem is that Perl doesn't implement the tri-state logic
> semantics that most users of null are used to, which is a different issue.
So, to paraphrase your statement a bit:
It is self-evident that they're the same, the problem is that they work
differently.
To the extent that both exist in computer language systems and can be mixed
with numbers in expressions, indeed, I must agree that they have similarities,
although I do not agree that they are the same. The fact that the functional
semantics of each are well-defined and quite different is sufficient to define
them as separate concepts.
Nota Bene: IEEE floating point defines two different concepts that are not
numbers, but can be mixed with numbers in expressions: Inf and NaN. And
actually, there are positive and negative varieties of both Inf and NaN. So I
guess you might say that they are the same; but the problem is that they work
differently. Which, of course, is the reason that the concepts are defined
separately.
--
Glenn
=====
Even if you're on the right track,
you'll get run over if you just sit there.
-- Will Rogers
_______________________________________________
Why pay for something you could get for free?
NetZero provides FREE Internet Access and Email
http://www.netzero.net/download/index.html
