From: skaller <skaller@users.sourceforge.net>
To: John Prevost <j.prevost@gmail.com>
Cc: Alex Baretta <alex@barettadeit.com>, Ocaml <caml-list@inria.fr>
Subject: Re: [Caml-list] Dummy polymorphic constructors
Date: 17 Dec 2004 18:59:37 +1100 [thread overview]
Message-ID: <1103270377.15260.27.camel@pelican.wigram> (raw)
In-Reply-To: <d849ad2a041216143853ab054@mail.gmail.com>
On Fri, 2004-12-17 at 09:38, John Prevost wrote:
> On Thu, 16 Dec 2004 20:22:57 +0100, Alex Baretta <alex@barettadeit.com> wrote:
> > Currently ocaml does not support empty polymorphic variant sum types.
> > Say, I cannot write the following.
> >
> > type empty = [ ]
> I'm somewhat confused as to why this is different from simply
> declaring a new opaque type:
>
> type empty
>
> Since there is no way to construct a value of the type, nor any way to
> deconstruct such a value, how is it different?
Polymorphic variants are extensible and algebraic ..
an abstract type is neither.
--
John Skaller, mailto:skaller@users.sf.net
voice: 061-2-9660-0850,
snail: PO BOX 401 Glebe NSW 2037 Australia
Checkout the Felix programming language http://felix.sf.net
next prev parent reply other threads:[~2004-12-17 7:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-16 19:22 Alex Baretta
2004-12-16 22:38 ` [Caml-list] " John Prevost
2004-12-17 7:42 ` Alex Baretta
2004-12-17 7:59 ` skaller [this message]
2004-12-17 1:10 ` Jacques Garrigue
2004-12-17 9:03 ` skaller
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