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 OAA15653; Tue, 6 Apr 2004 14:54:05 +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 OAA15284 for <caml-list@pauillac.inria.fr>; Tue, 6 Apr 2004 14:54:04 +0200 (MET DST)
Received: from pop19.ucdavis.edu (pop19.ucdavis.edu [169.237.105.29])
	by concorde.inria.fr (8.12.10/8.12.10) with ESMTP id i36Cs2YM025608
	for <caml-list@inria.fr>; Tue, 6 Apr 2004 14:54:03 +0200
Received: from mallorn (mallorn.ucdavis.edu [128.120.141.141])
	by pop19.ucdavis.edu (8.12.10/8.12.9/it-std-5.2.0) with SMTP id i36Cs1iI013948
	for <caml-list@inria.fr>; Tue, 6 Apr 2004 05:54:01 -0700 (PDT)
Received: by mallorn (sSMTP sendmail emulation); Tue,  6 Apr 2004 06:00:10 -0700
From: "Issac Trotts" <ijtrotts@ucdavis.edu>
Date: Tue, 6 Apr 2004 06:00:10 -0700
To: caml-list@inria.fr
Subject: Re: [Caml-list] Function forward declaration?
Message-ID: <20040406130010.GA29623@mallorn>
Mail-Followup-To: ijtrotts@ucdavis.edu, caml-list@inria.fr
References: <60532B15DF92FD4693AA89B2F7E01D8F013F29EC@tmex02> <87lll9wadk.dlv@vanicat.homelinux.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <87lll9wadk.dlv@vanicat.homelinux.org>
User-Agent: Mutt/1.5.5.1+cvs20040105i
X-Miltered: at concorde by Joe's j-chkmail ("http://j-chkmail.ensmp.fr")!
X-Loop: caml-list@inria.fr
X-Spam: no; 0.00; issac:01 trotts:01 ijtrotts:01 caml-list:01 2004:99 recurrence:01 issac:01 trotts:01 ijtrotts:01 ocaml:01 rec:01 rec:01 0200,:01 writes:01 remi:01 
Sender: owner-caml-list@pauillac.inria.fr
Precedence: bulk
X-Status: 
X-Keywords:                  
X-UID: 70

On Tue, Apr 06, 2004 at 02:37:11PM +0200, Remi Vanicat wrote:
> Timo.Tapiola@tietoenator.com writes:
> 
> > Hi,
> >
> > could someone tell me if there is some way to forward declare functions in
> > OCaml?
> 
> no, but you can :
> 
> use the "let rec ... and .. and ... " construct :
> 
> let rec simpl1 x y = simpl2 y x
> and simpl2 x y = simpl1 y x
> 
> or use local function :
> 
> let rec simpl1 x y =
>   let simpl2 x y = simpl1 y x in
>   simpl2 y x
> 
> You can even use both technique at the same time.
> 
> The third technique is less clean, and is rarely needed : it use
> references :
> 
> let simpl1_ref = ref (fun x -> assert false)
> 
> let simpl2 x y = !simpl1_ref y x
> let simpl1 x y = simpl2 x y
> let _ = simpl1_ref := simpl1
> 
> both two first method cover most of the case, the third one is needed
> only in very long code, or in recurrence between compilation unit.

This cleaner alternative should cover some of those cases:

    let simpl2 f x y = f y x
    let rec simpl1 x y = simpl2 simpl1 x y

-- 
Issac Trotts
http://mallorn.ucdavis.edu/~ijtrotts
(w) 530-757-8789

-------------------
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