From: Stefan Monnier <monnier@iro.umontreal.ca>
To: caml-list@inria.fr
Subject: Re: Equality of functional values
Date: Wed, 31 Jan 2007 02:03:53 -0500 [thread overview]
Message-ID: <jwvd54vy96q.fsf-monnier+gmane.comp.lang.caml.inria@gnu.org> (raw)
In-Reply-To: <45BFDF8C.20609@mcmaster.ca>
> I really meant 'Intensional equality', in other words, if they are the same
> as far as the system is concerned (in a logic this usually this means the
> same syntactically, but in the case of ocaml that would be pointer
> equality).
I don't know what the OCaml optimizer may do, but I do know that in SML/NJ
such an intentional equality would often not give the expected result,
because it's pretty common for it to use various forms of eta-like
expansions in the hope of doing uncurrying or argument flattening, so you
may end up with
f == f
turned into
(λx1.λx2.f(x1,x2)) == (λy1.λy2.f(y1,y2))
and the system may not try to recognize that the two lambda-expressions are
identical (too costly an analysis for no performance benefit), so it will
compile them to two different pieces of machine language.
Stefan
next prev parent reply other threads:[~2007-01-31 7:04 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-29 21:04 Simon Frost
2007-01-29 21:11 ` [Caml-list] " Tom
2007-01-29 21:23 ` Brian Hurt
2007-01-29 21:59 ` Gerd Stolpmann
2007-01-30 8:17 ` Christophe Raffalli
2007-01-30 8:45 ` David MENTRE
2007-01-30 13:24 ` Andrej Bauer
2007-01-30 13:55 ` skaller
2007-01-30 14:21 ` Brian Hurt
2007-01-30 15:21 ` Jeff Polakow
2007-01-30 15:49 ` Jacques Carette
2007-01-30 17:23 ` Chris King
2007-01-30 20:18 ` Tom
2007-01-30 20:30 ` Gerd Stolpmann
2007-01-30 20:41 ` Fernando Alegre
2007-01-30 21:01 ` Christophe TROESTLER
2007-01-30 21:08 ` Tom
2007-01-30 21:46 ` Christophe TROESTLER
2007-01-30 22:05 ` Fernando Alegre
2007-01-30 23:13 ` skaller
2007-01-30 23:06 ` Andrej Bauer
2007-01-31 0:15 ` Jacques Carette
2007-01-31 7:03 ` Stefan Monnier [this message]
2007-01-31 12:54 ` [Caml-list] " Jacques Carette
2007-01-31 0:15 ` [Caml-list] " skaller
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