Pardon me, but I have to vent some spleen.
Whose brilliant idea was it to make "/=" be not equal??? I just spent too
damn long tracking down a bug which occurred when someone used "\=" when
they meant "/=". What a nasty failure mode for an easy-to-make,
hard-to-spot typo! What's wrong with "<>"?
*grumble*
Larry
--
Lawrence Hunter, PhD.
National Library of Medicine
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Bethesda. MD 20894 USA
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What's wrong with "<>"?
Using <> to mean `less than or greater than' much in the same way that
<= means `less then or equal to' only makes sense for domains that are
orderable (like the reals). `Not equal' is a more general notion that applies
even to unordered domains like complex numbers. Hence the metaphor of <> would
be inappropriate for a `not equals' predicate.
Jeff
<My rant about the stupidity of "/=" for not-equal deleted>
What's wrong with "<>"?
Using <> to mean `less than or greater than' much in the same way that <=
means `less then or equal to' only makes sense for domains that are
orderable (like the reals).
OK, fine, good point. How about "n="
--
Lawrence Hunter, PhD.
National Library of Medicine
Bldg. 38A, MS-54
Bethesda. MD 20894 USA
tel: +1 (301) 496-9300
fax: +1 (301) 496-0673
internet: ······@nlm.nih.gov
encryption: public key via RIPEM server or "finger ······@work.nlm.nih.gov"
In article <·················@qobi.ai.toronto.edu>, ····@qobi.ai.toronto.edu (Jeffrey Mark Siskind) writes:
|> What's wrong with "<>"?
|>
|> Using <> to mean `less than or greater than' much in the same way that
|> <= means `less then or equal to' only makes sense for domains that are
|> orderable (like the reals). `Not equal' is a more general notion that applies
|> even to unordered domains like complex numbers. Hence the metaphor of <> would
|> be inappropriate for a `not equals' predicate.
|> Jeff
By your reasoning, /= (ie divide equals) doesn't make much sense either. My
personal preference would have been !=. I've often seen ! to mean not, hence !=
means not equal.
Mike McDonald Advanced Technology Dept.
Harris Corp.
Email: ···@trantor.harris-atd.com M.S. 16-1912
Voice: (407) 727-5060 P.O. Box 37
Fax: (407) 729-3363 Melbourne, Florida 32902
In article <··········@jabba.ess.harris.com> ···@trantor.harris-atd.com (Mike McDonald) writes:
By your reasoning, /= (ie divide equals) doesn't make much sense either.
My
personal preference would have been !=. I've often seen ! to mean not,
hence !=
means not equal.
`!' meaning `not' is a metaphor particular to some languages and not others.
For instance, in conventional mathematical notations `!' means factorial and
`~' or the TeX symbol $\neg$ means `not'. Traditional mathematical notation
uses a slash through an infix predicate symbol to mean its negation, as in
the TeX symbol $\not=$. I assume that using /= to mean `not equal' derives from
that tradition. Furthermore, since traditionally a forward slash through a
symbol is used to indicate negation, not a backslash, /= is a reasonable
metaphor in contrast to \=. This fortuitously jives with the fact that in
CommonLisp (like C for that matter), \ is an escape character while / is not.
Jeff
In article <··········@jabba.ess.harris.com> ···@trantor.harris-atd.com (Mike McDonald) writes:
> By your reasoning, /= (ie divide equals) doesn't make much sense either. My
>personal preference would have been !=. I've often seen ! to mean not, hence !=
>means not equal.
I've only seen ! used to mean "not" in C. At the time CL was being
designed C wasn't nearly as popular as it is now. If they were going to
steal from another language, Pascal probably would have been the language
of choice at the time. I don't remember what it uses as "not" (perhaps
"~", as in PL/I?).
/= was chosen because it almost looks like the mathematical not-equals
sign. Most people write that as an equals sign with a diagonal slash.
Perhaps a better choice would have been =/=.
--
Barry Margolin
System Manager, Thinking Machines Corp.
······@think.com {uunet,harvard}!think!barmar
In article <············@early-bird.think.com>, ······@think.com (Barry Margolin) writes:
|> In article <··········@jabba.ess.harris.com> ···@trantor.harris-atd.com (Mike McDonald) writes:
|> > By your reasoning, /= (ie divide equals) doesn't make much sense either. My
|> >personal preference would have been !=. I've often seen ! to mean not, hence !=
|> >means not equal.
|>
|> I've only seen ! used to mean "not" in C. At the time CL was being
I've seen ! used for not in boolean logic, ie !(A + B). It's hard to draw a bar
over things in ascii.
|> designed C wasn't nearly as popular as it is now. If they were going to
|> steal from another language, Pascal probably would have been the language
|> of choice at the time. I don't remember what it uses as "not" (perhaps
|> "~", as in PL/I?).
Pascal uses <>.
|> /= was chosen because it almost looks like the mathematical not-equals
|> sign. Most people write that as an equals sign with a diagonal slash.
|> Perhaps a better choice would have been =/=.
|> --
|> Barry Margolin
|> System Manager, Thinking Machines Corp.
|>
|> ······@think.com {uunet,harvard}!think!barmar
To me, /= just doesn't look like a slash thru an equals sign. Not that it
matters much now.
Mike McDonald Advanced Technology Dept.
Harris Corp.
Email: ···@trantor.harris-atd.com M.S. 16-1912
Voice: (407) 727-5060 P.O. Box 37
Fax: (407) 729-3363 Melbourne, Florida 32902
In article <··········@jabba.ess.harris.com> ···@trantor.harris-atd.com (Mike McDonald) writes:
In article <············@early-bird.think.com>, ······@think.com (Barry Margolin) writes:
[...]
|> designed C wasn't nearly as popular as it is now. If they were going to
|> steal from another language, Pascal probably would have been the language
|> of choice at the time. I don't remember what it uses as "not" (perhaps
|> "~", as in PL/I?).
Pascal uses <>.
Depends on what you answer to. "not" in Pascal is written "not". "not equal"
is, as you say, written "<>"
[...]
To me, /= just doesn't look like a slash thru an equals sign. Not that it
matters much now.
Neither does it to me. =/= does, on the other hand, but it's (gasp) all those
3 characters :-).
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