From: "Grünewald Michaël" <michaelgrunewald@yahoo.fr>
To: AUGER Cedric <sedrikov@gmail.com>
Cc: David Rajchenbach-Teller <David.Teller@ens-lyon.org>,
Su Zhang <westlifezs@gmail.com>,
caml-list@yquem.inria.fr
Subject: Re: [Caml-list] how can I express empty element?
Date: Tue, 10 Mar 2009 09:47:38 +0100 [thread overview]
Message-ID: <89C1F57E-4FCC-4FA6-B600-B426A2CAC326@yahoo.fr> (raw)
In-Reply-To: <49B51619.9010306@lri.fr>
Le 9 mars 09 à 14:14, AUGER Cedric a écrit :
>
> David Rajchenbach-Teller wrote:
>> No, that's not possible. :: is an algebraic constructor, which means,
>> among other things, that it accepts no neutral element (well, except
>> when the list is infinite, but that's probably not what you're
>> looking
>> for).
>>
> And even if the list is infinite, I don't see any way to do it;
> but you can always define:
If `l' is only infinite list with type `unit list', then `l' is a
neutral element for `::' constructor, but only for `unit list'.
(Well, that is reminiscent of your favourite «consider a topological
space with two points, one open and one closed»-example, but I did not
find a better one!)
--
Cheers,
Michaël G.
prev parent reply other threads:[~2009-03-10 8:48 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-09 3:59 Su Zhang
2009-03-09 13:03 ` [Caml-list] " David Rajchenbach-Teller
2009-03-09 13:14 ` AUGER Cedric
2009-03-09 16:07 ` Laurent Le Brun
2009-03-10 8:47 ` Grünewald Michaël [this message]
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