From mboxrd@z Thu Jan  1 00:00:00 1970
Received: (from majordomo@localhost) by pauillac.inria.fr (8.7.6/8.7.3) id VAA08109; Tue, 3 Aug 2004 21:57:47 +0200 (MET DST)
X-Authentication-Warning: pauillac.inria.fr: majordomo set sender to owner-caml-list@pauillac.inria.fr using -f
Received: from concorde.inria.fr (concorde.inria.fr [192.93.2.39]) by pauillac.inria.fr (8.7.6/8.7.3) with ESMTP id VAA07589 for <caml-list@pauillac.inria.fr>; Tue, 3 Aug 2004 21:57:46 +0200 (MET DST)
Received: from mail5.speakeasy.net (mail5.speakeasy.net [216.254.0.205])
	by concorde.inria.fr (8.12.10/8.12.10) with ESMTP id i73JviRM014120
	for <caml-list@inria.fr>; Tue, 3 Aug 2004 21:57:44 +0200
Received: (qmail 5537 invoked from network); 3 Aug 2004 19:57:41 -0000
Received: from shell2.speakeasy.net ([69.17.110.71])
          (envelope-sender <brogoff@speakeasy.net>)
          by mail5.speakeasy.net (qmail-ldap-1.03) with AES256-SHA encrypted SMTP
          for <caml-list@inria.fr>; 3 Aug 2004 19:57:41 -0000
Date: Tue, 3 Aug 2004 12:57:40 -0700 (PDT)
From: brogoff <brogoff@speakeasy.net>
To: Ocaml Mailing List <caml-list@inria.fr>
Subject: Re: [Caml-list] Functors and classes
In-Reply-To: <d849ad2a04080308285605bb7e@mail.gmail.com>
Message-ID: <Pine.LNX.4.58.0408031252530.22016@shell2.speakeasy.net>
References: <20040803120244.GA22304@annexia.org> <20040803121049.GA22418@annexia.org>
 <20040803131716.GA22773@annexia.org> <d849ad2a04080308062629fb25@mail.gmail.com>
 <20040803151241.GA25124@annexia.org> <d849ad2a04080308277a3dbf21@mail.gmail.com>
 <d849ad2a04080308285605bb7e@mail.gmail.com>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
X-Miltered: at concorde with ID 410FEE38.000 by Joe's j-chkmail (http://j-chkmail.ensmp.fr)!
X-Loop: caml-list@inria.fr
X-Spam: no; 0.00; brogoff:01 brogoff:01 caml-list:01 functors:01 prevost:01 val:01 val:01 struct:01 demonstrate:01 stab:01 caveat:01 struct:01 conn:01 conn:01 blah:01 
Sender: owner-caml-list@pauillac.inria.fr
Precedence: bulk

On Tue, 3 Aug 2004, John Prevost wrote:
> Oops.  A couple of errors in that last thing I wrote that weren't the
> problem I was trying to illustrate (that's what I get for trying fixes
> inline before giving up):
>
> module type ThingPoolT =
>   sig
>     type connection
>     val connect : unit -> connection
>     val test : connection -> int
>   end
>
> module ThingPool (Thing : ThingIntf) :
>     (ThingPoolT with type connection = Thing.connection) =
>   struct
>     type connection = Thing.connection
>     let connect () = Thing.connect ()
>     let test x = x#a + 1
>   end

Certainly if you're going to call method a it needs to be exposed. If I
understand the problems you're trying to demonstrate, the following would be
my stab at it. Untested code, caveat emptor, blah blah blah...

module type ThingIntf =
  sig
    type 'a connection =
        'a constraint 'a = < a: int; connect : unit -> 'a connection; ..>
    val connect : unit -> 'a connection
  end;;

module type ThingPoolT =
  sig
    include ThingIntf
    val test : 'a connection -> int
  end;;

module ThingPool (Thing : ThingIntf) : ThingPoolT =
  struct
    include Thing

    let connect () =
      let conn = Thing.connect () in
      ignore (conn#a);
      conn

    let (test : _ connection -> int) = fun x -> x#a + 1
  end;;

-- Brian

-------------------
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners