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[Caml-list] Stupid question
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Date: 2004-01-15 (03:57)
From: skaller <skaller@t...>
Subject: Re: [Caml-list] Stupid question
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.
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