From: Stephen Dolan <stephen.dolan@cl.cam.ac.uk>
To: Andreas Rossberg <rossberg@mpi-sws.org>
Cc: Gabriel Scherer <gabriel.scherer@gmail.com>,
Julien Blond <julien.blond@gmail.com>,
David Allsopp <dra-news@metastack.com>,
OCaml mailing-list <caml-list@inria.fr>
Subject: Re: [Caml-list] Empty polymorphic variant set
Date: Fri, 25 Nov 2016 16:50:19 +0000 [thread overview]
Message-ID: <CA+mHimNSxnZp3AgxYZkzSq3y1DH_XsB65_pzFbyNPBJu_qSuTA@mail.gmail.com> (raw)
In-Reply-To: <3AD797C1-47D8-4521-9CEF-03D12CDF6867@mpi-sws.org>
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On Fri, Nov 25, 2016 at 1:52 PM, Andreas Rossberg <rossberg@mpi-sws.org>
wrote:
>
> > On Nov 25, 2016, at 14:46 , Gabriel Scherer <gabriel.scherer@gmail.com>
> wrote:
> >
> > I would agree that OCaml lacks a convenient way to define the empty
> > type.
>
> Isn’t
>
> type empty
>
> (as a definition) a sufficiently convenient way to define an empty type?
>
I agree that that defines the empty type, but OCaml disagrees. OCaml takes
that as declaring an abstract type, just as if you'd included a module
exposing an opaque type. So, the compiler won't conclude that 'empty' is
actually an empty type (viewing it as an unknown abstract type), nor will
it refute (int, empty) eq.
Stephen
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next prev parent reply other threads:[~2016-11-25 16:50 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-25 8:39 Julien Blond
2016-11-25 9:19 ` Ben Millwood
2016-11-25 9:20 ` Julien Blond
2016-11-25 11:22 ` David Allsopp
2016-11-25 13:01 ` Julien Blond
2016-11-25 13:46 ` Gabriel Scherer
2016-11-25 13:52 ` Andreas Rossberg
2016-11-25 15:42 ` Markus Mottl
2016-11-25 15:46 ` Gabriel Scherer
2016-11-25 15:59 ` Yaron Minsky
2016-11-25 16:42 ` Markus Mottl
2016-11-25 17:11 ` Gabriel Scherer
2016-11-25 16:50 ` Stephen Dolan [this message]
2016-11-25 16:59 ` Jeremy Yallop
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