From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mail4-relais-sop.national.inria.fr (mail4-relais-sop.national.inria.fr [192.134.164.105])
	by walapai.inria.fr (8.13.6/8.13.6) with ESMTP id p2JFgZp4021728
	for <caml-list@sympa-roc.inria.fr>; Sat, 19 Mar 2011 16:42:35 +0100
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: Ai4EAB5shE3RVdY0kGdsb2JhbACYfIxwCBQBAQIJCRQUBCGoEIpCgh+ERy+IWwEBAwWFXgSMZ4RDhDw6
X-IronPort-AV: E=Sophos;i="4.63,211,1299452400"; 
   d="scan'208";a="90753399"
Received: from mail-bw0-f52.google.com ([209.85.214.52])
  by mail4-smtp-sop.national.inria.fr with ESMTP/TLS/RC4-SHA; 19 Mar 2011 16:42:30 +0100
Received: by bwj24 with SMTP id 24so5291607bwj.39
        for <caml-list@yquem.inria.fr>; Sat, 19 Mar 2011 08:42:29 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=gmail.com; s=gamma;
        h=domainkey-signature:from:to:subject:date:user-agent:mime-version
         :content-type:content-transfer-encoding:message-id;
        bh=jJhk7Sg4E7161gfQFElsdgkv5gxURkAFGfQPeIXQHgI=;
        b=KRlEtOEnnNjTQdlXCAc+o76j+lQ7qc5GhFIWQX6BxUXBIs6Wui4ZzbmzFcQn9YtukM
         gQO2fZg19B9Z9GegbhL+DAFPw4H36vDxg3rgEMe3K2dbREauz1YK9JaV7Euj4y/oYeTn
         mwW2HRmLA3JFaQswk2LhTb2AbbByplfHOzsQk=
DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=gamma;
        h=from:to:subject:date:user-agent:mime-version:content-type
         :content-transfer-encoding:message-id;
        b=SLEZrGLwYCFC7d799PnQB0G7cSkBy3CZFSqkmlgapynId32vKyXZXtTDqdfz7+ztng
         ST8hIpQABAZ4HN6if5UQ66VRe2+nhZ+pZeSd8J/L/bDp6CfiXwY4EyaWHZHHcU73TVT1
         lQoAfl2HG6OH5JwXWdg7ZV4y/iAOv7Czb2fWw=
Received: by 10.204.47.87 with SMTP id m23mr1987276bkf.156.1300549349226;
        Sat, 19 Mar 2011 08:42:29 -0700 (PDT)
Received: from cloudy.localnet ([85.69.95.49])
        by mx.google.com with ESMTPS id k5sm2961724bku.16.2011.03.19.08.42.27
        (version=SSLv3 cipher=OTHER);
        Sat, 19 Mar 2011 08:42:28 -0700 (PDT)
From: Raphael Proust <raphlalou@gmail.com>
To: caml-list@yquem.inria.fr
Date: Sat, 19 Mar 2011 16:48:40 +0100
User-Agent: KMail/1.13.6 (Linux/2.6.37-ARCH; KDE/4.6.1; i686; ; )
MIME-Version: 1.0
Content-Type: text/plain;
  charset="iso-8859-1"
Message-Id: <201103191648.40345.raphlalou@gmail.com>
Content-Transfer-Encoding: 8bit
X-MIME-Autoconverted: from quoted-printable to 8bit by walapai.inria.fr id p2JFgZp4021728
Subject: [Caml-list] Recursive Parametric class type Typing

Hi list,

Trying to bind a javascript library for js_of_ocaml, I encountered the following
pattern (here drastically simplified):

class type ['t] c =
  object
    method plus: 't -> unit
    method minus: unit -> 't
    method container: unit -> container
  end
and container =
  object
    method int: unit -> int c
    method string: unit -> string c
  end

The following error is raised at compile time:
Error: This type string should be an instance of type int

In the use case:
- instead of [int] and [string] there are six different [class type]s;
- [classe type]s have more methods; and
- there are additional recursive [class type]s


Why is there such a limitation on the types? Is there a work around that
wouldn't induce (too  much) code duplication?

Thanks,
-- 
______________
Raphaël Proust