From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <garrigue@math.nagoya-u.ac.jp>
Received: from mail2-relais-roc.national.inria.fr (mail2-relais-roc.national.inria.fr [192.134.164.83])
	by sympa.inria.fr (Postfix) with ESMTPS id 0C8C17EE25
	for <caml-list@sympa.inria.fr>; Fri,  1 Nov 2013 00:43:11 +0100 (CET)
Received-SPF: None (mail2-smtp-roc.national.inria.fr: no sender
  authenticity information available from domain of
  garrigue@math.nagoya-u.ac.jp) identity=pra;
  client-ip=133.6.130.5;
  receiver=mail2-smtp-roc.national.inria.fr;
  envelope-from="garrigue@math.nagoya-u.ac.jp";
  x-sender="garrigue@math.nagoya-u.ac.jp";
  x-conformance=sidf_compatible
Received-SPF: None (mail2-smtp-roc.national.inria.fr: no sender
  authenticity information available from domain of
  garrigue@math.nagoya-u.ac.jp) identity=mailfrom;
  client-ip=133.6.130.5;
  receiver=mail2-smtp-roc.national.inria.fr;
  envelope-from="garrigue@math.nagoya-u.ac.jp";
  x-sender="garrigue@math.nagoya-u.ac.jp";
  x-conformance=sidf_compatible
Received-SPF: None (mail2-smtp-roc.national.inria.fr: no sender
  authenticity information available from domain of
  postmaster@mailhost.math.nagoya-u.ac.jp) identity=helo;
  client-ip=133.6.130.5;
  receiver=mail2-smtp-roc.national.inria.fr;
  envelope-from="garrigue@math.nagoya-u.ac.jp";
  x-sender="postmaster@mailhost.math.nagoya-u.ac.jp";
  x-conformance=sidf_compatible
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: AuwBAB3qclKFBoIFnGdsb2JhbABZDocOvF+BOQ4BAQEBAQgUCTyCJQEBBAEjIAE1AgMLCQIaAhgOAgJXBhOIAQWOMppodoNjAoVjiQ0HgSmNczMHgms1gQ6JQY5MlHBO
X-IPAS-Result: AuwBAB3qclKFBoIFnGdsb2JhbABZDocOvF+BOQ4BAQEBAQgUCTyCJQEBBAEjIAE1AgMLCQIaAhgOAgJXBhOIAQWOMppodoNjAoVjiQ0HgSmNczMHgms1gQ6JQY5MlHBO
X-IronPort-AV: E=Sophos;i="4.93,613,1378850400"; 
   d="scan'208";a="40059008"
Received: from rabbit.math.nagoya-u.ac.jp (HELO mailhost.math.nagoya-u.ac.jp) ([133.6.130.5])
  by mail2-smtp-roc.national.inria.fr with ESMTP; 01 Nov 2013 00:42:50 +0100
Received: from mailhost.math.nagoya-u.ac.jp (localhost [127.0.0.1])
	by mailhost.math.nagoya-u.ac.jp (Postfix) with ESMTP id 416B063A1;
	Fri,  1 Nov 2013 08:43:05 +0900 (JST)
Received: from mailhost.math.nagoya-u.ac.jp (localhost [127.0.0.1])
	by mailhost.math.nagoya-u.ac.jp (Postfix) with ESMTP id EDA5540D0;
	Fri,  1 Nov 2013 08:43:04 +0900 (JST)
DomainKey-Signature: h=Received:Content-Type:Mime-Version:Subject:From:In-Reply-To:Date:Cc:Content-Transfer-Encoding:Message-Id:References:To:X-Mailer; b=; c=nofws; d=math.nagoya-u.ac.jp; q=; s=alpha
Received: from tet.garrigue.jp (58x158x128x157.ap58.ftth.ucom.ne.jp [58.158.128.157])
	by mailhost.math.nagoya-u.ac.jp (Postfix) with ESMTPSA id 9D9D239AD;
	Fri,  1 Nov 2013 08:43:04 +0900 (JST)
Content-Type: text/plain; charset=utf-8
Mime-Version: 1.0 (Mac OS X Mail 7.0 \(1816\))
From: Jacques Garrigue <garrigue@math.nagoya-u.ac.jp>
In-Reply-To: <D3CAEFBB-C3D5-4FCF-9291-25F380E33798@dpmms.cam.ac.uk>
Date: Fri, 1 Nov 2013 08:43:03 +0900
Cc: caml-list <caml-list@yquem.inria.fr>
Content-Transfer-Encoding: quoted-printable
Message-Id: <98AF3DB4-B0DF-4958-9283-39E849520B29@math.nagoya-u.ac.jp>
References: <D3CAEFBB-C3D5-4FCF-9291-25F380E33798@dpmms.cam.ac.uk>
To: Nicolas Ojeda Bar <N.Ojeda.Bar@dpmms.cam.ac.uk>
X-Mailer: Apple Mail (2.1816)
Subject: Re: [Caml-list] recursive types and modules problem

2013/11/01 5:13=E3=80=81Nicolas Ojeda Bar <N.Ojeda.Bar@dpmms.cam.ac.uk> =E3=
=81=AE=E3=83=A1=E3=83=BC=E3=83=AB=EF=BC=9A

> What is the best way to rewrite the following recursive definitions so th=
at
> I can actually compile them?
>=20
> S =3D Set.Make (struct type t =3D t1 let compare x1 x2 =3D x1.stamp - x2.=
stamp end)
>=20
> type t1 =3D {
>  stamp : int;
>  x : t2
> }
>=20
> and t2 =3D {
>  y : S.t
> }

A slightly shorter version, using the fact that recursive modules containin=
g only
types require no implementation:

module rec T : sig
  type t1 =3D { stamp: int; x: t2 }
  and t2 =3D { y: S.t }
end =3D T
and S : Set.S with type elt =3D T.t1 =3D
  Set.Make
    (struct open T type t =3D t1 let compare x1 x2 =3D x1.stamp - x2.stamp =
end)

Jacques Garrigue