From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <nicolas.pouillard@gmail.com>
X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on yquem.inria.fr
X-Spam-Level: *
X-Spam-Status: No, score=1.1 required=5.0 tests=AWL,SPF_NEUTRAL 
	autolearn=disabled version=3.1.3
X-Original-To: caml-list@yquem.inria.fr
Delivered-To: caml-list@yquem.inria.fr
Received: from discorde.inria.fr (discorde.inria.fr [192.93.2.38])
	by yquem.inria.fr (Postfix) with ESMTP id 72923BC0A
	for <caml-list@yquem.inria.fr>; Mon,  4 Jun 2007 22:14:01 +0200 (CEST)
Received: from wa-out-1112.google.com (wa-out-1112.google.com [209.85.146.178])
	by discorde.inria.fr (8.13.6/8.13.6) with ESMTP id l54KE0HB024767
	for <caml-list@yquem.inria.fr>; Mon, 4 Jun 2007 22:14:00 +0200
Received: by wa-out-1112.google.com with SMTP id j37so2151524waf
        for <caml-list@yquem.inria.fr>; Mon, 04 Jun 2007 13:13:59 -0700 (PDT)
DKIM-Signature: a=rsa-sha1; c=relaxed/relaxed;
        d=gmail.com; s=beta;
        h=domainkey-signature:received:received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references;
        b=oKy0lzX1ullYYn7yAS2il6FHXDTAKp/+H7uLipZrxeoPfk30meXD3YvnmtPzxEgbx3W6UjA+8vhBZw2OdbHcAb4ctbU2kmitcYVNvim/JspY3jymmYHg2oKFVhTBdTbMVWuD2dLPRQmyT7fVextZmgDYAnTuoXem5OagH6AfXXY=
DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=beta;
        h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references;
        b=fjR7oU+aw0EULEro1OZkMWNhel72dFHvuWghUx/jMe4XANBoggS9gCvN7sVD+hvQ8nBs556o112MRXzJAAHIsiCSbfEXb4ITsR+cpszdA0CLkxHNSNuyw2Qel4q+O7lqkBwI+3I9GDK18Ct0cfQUr0eoH7N/aJf+mo1UzxZBK/E=
Received: by 10.115.22.1 with SMTP id z1mr2853384wai.1180988039145;
        Mon, 04 Jun 2007 13:13:59 -0700 (PDT)
Received: by 10.114.181.8 with HTTP; Mon, 4 Jun 2007 13:13:59 -0700 (PDT)
Message-ID: <cd67f63a0706041313sc3680a9j258c92213460e1b8@mail.gmail.com>
Date: Mon, 4 Jun 2007 22:13:59 +0200
From: "Nicolas Pouillard" <nicolas.pouillard@gmail.com>
To: "Raj B" <rajb@rice.edu>
Subject: Re: [Caml-list] OCaml object types vs record types
Cc: caml-list@yquem.inria.fr
In-Reply-To: <0EE1C559-A93C-4E66-AC70-8ADD1C21DDF8@rice.edu>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
References: <0EE1C559-A93C-4E66-AC70-8ADD1C21DDF8@rice.edu>
X-j-chkmail-Score: MSGID : 46647288.000 on discorde : j-chkmail score : X : 0/20 1 0.000 -> 1
X-Miltered: at discorde with ID 46647288.000 by Joe's j-chkmail (http://j-chkmail . ensmp . fr)!
X-Spam: no; 0.00; ocaml:01 subtyping:01 mutable:01 ocaml:01 foo:01 mutable:01 wrote:01 caml-list:01 coercion:01 int:01 int:01 objects:02 string:02 string:02 garrigue:03 

On 6/4/07, Raj B <rajb@rice.edu> wrote:
> Hi there
>
> I'm writing an application where I'd modeling objects as record
> types. However, I'd like to have a subtyping relation between them
> along with (occasional) coercion. For example,
>
> type obj = {name : string}
> type specialobj = {name: string; mutable value: int;...}
> and so on...
>

The pa_oo extension from Jacques Garrigue  does exactly this kind of things:

http://www.math.nagoya-u.ac.jp/~garrigue/code/ocaml.html
(works also in 3.10 but not released yet, contact me if you want it)

Example:

type obj = <name : string>
type specialobj = <name: string; value: int; set_value: int -> unit...>

let o = {| name = "foo"; mutable value = 42 |}
in o#name, o#value <- 43, o#value

Regards,

-- 
Nicolas Pouillard