From: Leo White <lpw25@cam.ac.uk>
To: Ben Millwood <bmillwood@janestreet.com>
Cc: Jeremy Yallop <yallop@gmail.com>,
David Allsopp <dra-news@metastack.com>,
OCaml List <caml-list@inria.fr>
Subject: Re: [Caml-list] Match error with abstract types in modules
Date: Tue, 24 Feb 2015 21:11:32 +0000 [thread overview]
Message-ID: <87k2z72ewr.fsf@study.localdomain> (raw)
In-Reply-To: <CA+MHO50VZUavWk2A-shNqUEV8uEw-dtFuFP=uGZ+_MMRTgFjDg@mail.gmail.com> (Ben Millwood's message of "Tue, 24 Feb 2015 20:03:58 +0000")
Ben Millwood <bmillwood@janestreet.com> writes:
> I think the issue would be substantially mitigated were it not for the simple fact that [type 'a t] in a signature
> means "abstract type", whereas [type 'a t] in a structure means "empty type". The fact that there is no syntactic
> distinction, and indeed *no way to make one* caused me a great deal of confusion some time ago when I had a problem
> similar to David's.
You can make an empty type (or at least a type for which there are no
expressions) using:
type 'a t = private T
next prev parent reply other threads:[~2015-02-24 21:11 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-24 17:25 David Allsopp
2015-02-24 18:02 ` Leo White
2015-02-24 18:26 ` David Allsopp
2015-02-24 19:11 ` Leo White
2015-02-25 8:41 ` David Allsopp
2015-02-24 19:52 ` Jeremy Yallop
2015-02-24 20:03 ` Ben Millwood
2015-02-24 21:11 ` Leo White [this message]
2015-02-25 8:41 ` David Allsopp
2015-02-25 9:48 ` Gabriel Scherer
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