From: "Stéphane Lescuyer" <lescuyer@lri.fr>
To: "Damien Guichard" <alphablock@orange.fr>
Cc: "Liste de diffusion OCaml" <caml-list@inria.fr>
Subject: Re: [Caml-list] Variants & structural ordering
Date: Tue, 5 Feb 2008 18:25:32 +0100 [thread overview]
Message-ID: <e9e94ac90802050925t45506404id7ced8f27f15e867@mail.gmail.com> (raw)
In-Reply-To: <20080205165714.DE06A7000C0E@mwinf2354.orange.fr>
2008/2/5 Damien Guichard <alphablock@orange.fr>:
> And the answer is: OCaml variants are certainly treated as an initial
> algebra, but not exactly as an enumeration, thus their relative order is not
> meaningfull to the compare function.
Actually it *is* meaningful, but as Berke pointed out, constant
constructors and variant expecting some arguments are treated (and
ordered) separately.
This is explained in detail in Sec. 18.3.4 of the manual
[http://caml.inria.fr/pub/docs/manual-ocaml/manual032.html], and this
is why adding dummy arguments of type unit does the trick.
My point is that it's not as bad as it looks, since you have a way to
"control" (or at least predict) what the order between your different
values will be. This is a difference with polymorphic variants for
instance.
--
Stéphane L.
http://www.lri.fr/~lescuyer
next prev parent reply other threads:[~2008-02-05 17:25 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-05 16:59 Damien Guichard
2008-02-05 17:25 ` Stéphane Lescuyer [this message]
-- strict thread matches above, loose matches on Subject: below --
2008-02-05 8:21 Damien Guichard
2008-02-05 9:47 ` [Caml-list] " Berke Durak
2008-02-05 9:48 ` Oliver Bandel
2008-02-05 15:04 ` Jon Harrop
2008-02-06 8:21 ` Michaël Grünewald
2008-02-07 15:50 ` Damien Doligez
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