From: skaller <skaller@tpg.com.au>
To: Brian Hurt <bhurt@spnz.org>
Cc: Ocaml Mailing List <caml-list@inria.fr>
Subject: Re: [Caml-list] Stupid question
Date: 15 Jan 2004 14:57:22 +1100 [thread overview]
Message-ID: <1074139041.7527.2.camel@localhost.localdomain> (raw)
In-Reply-To: <Pine.LNX.4.44.0401141350450.4373-100000@localhost.localdomain>
On Thu, 2004-01-15 at 11:03, Brian Hurt wrote:
> I was poking around in the produced assembly code of some ocaml code of
> mine, and I noticed something. The construct:
> if (x < m) <> (y < m) then
> ...
>
> when the compiler knows that x, y, and m are all ints, it calls an
> external C routine to compare the two booleans. But the construct:
>
> if (x < m) != (y < m) then
> ...
>
> does not. Now, this isn't a big deal- I just replaced <> with != and no
> problem. But I was kind of interested in why the compiler didn't catch
> and optimize this. Is there some sort of subtle semantic difference I'm
> too dense to see?
Well, <> is a polymorphic value comparison.
Whereas != is a physical inequality comparison.
--
John Max Skaller, mailto:skaller@tpg.com.au
snail:25/85c Wigram Rd, Glebe, NSW 2037, Australia.
voice:61-2-9660-0850. Checkout Felix: http://felix.sf.net
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next prev parent reply other threads:[~2004-01-15 3:57 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-01-15 0:03 Brian Hurt
2004-01-15 3:57 ` skaller [this message]
2004-01-15 6:13 ` Brian Hurt
2004-01-15 8:37 ` Christophe Raffalli
2004-01-16 0:43 ` Jacques Garrigue
2004-01-16 2:35 ` Brian Hurt
2004-01-16 8:40 ` Hendrik Tews
2004-01-16 10:25 ` Frederic van der Plancke
2004-01-16 12:07 ` Alex Baretta
2004-01-16 5:41 ` Nicolas Cannasse
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