From: Jean-Christophe Filliatre <Jean-Christophe.Filliatre@lri.fr>
To: Keiko Nakata <keiko@kurims.kyoto-u.ac.jp>
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] a module with multiple signatures
Date: Thu, 2 Jun 2005 10:04:07 +0200 [thread overview]
Message-ID: <17054.48503.615769.712007@gargle.gargle.HOWL> (raw)
In-Reply-To: <20050602.161836.68553253.keiko@kurims.kyoto-u.ac.jp>
Keiko Nakata writes:
>
> I tried to give a module different signatures through an use of functors.
> Then I faced a situation for which I do not understand the reason.
>
> This is the simplified version of my situation.
> [...]
> Anyway,
> there may be a nicer way to give a module multiple signatures
> while avoiding duplicate type declarations as possible?
> (In the above setting, I want to make the type s in M abstract in some
> context, but transparent in another context.)
I think you can proceed as follows:
module M = struct type s type t = A | B end
module M1 : sig type t = M.t = A | B end = M
module M2 : ... = M
i.e. you cannot put only "t = M.t" in the signature of M1, you need to
add "= A|B". This is called a "re-exported variant type" in Ocaml's
manual (see http://caml.inria.fr/pub/docs/manual-ocaml/manual018.html)
--
Jean-Christophe
prev parent reply other threads:[~2005-06-02 8:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-06-02 7:18 Keiko Nakata
2005-06-02 7:53 ` [Caml-list] " Julien Signoles
2005-06-02 11:15 ` Keiko Nakata
2005-06-02 12:08 ` Julien Signoles
2005-06-02 8:04 ` Jean-Christophe Filliatre [this message]
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