From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on yquem.inria.fr X-Spam-Level: X-Spam-Status: No, score=0.0 required=5.0 tests=AWL autolearn=disabled version=3.1.3 X-Original-To: caml-list@yquem.inria.fr Delivered-To: caml-list@yquem.inria.fr Received: from concorde.inria.fr (concorde.inria.fr [192.93.2.39]) by yquem.inria.fr (Postfix) with ESMTP id 7A71CBC0A for ; Tue, 3 Apr 2007 14:14:10 +0200 (CEST) Received: from pih-relay05.plus.net (pih-relay05.plus.net [212.159.14.132]) by concorde.inria.fr (8.13.6/8.13.6) with ESMTP id l33CE9F9018743 (version=TLSv1/SSLv3 cipher=AES256-SHA bits=256 verify=NO) for ; Tue, 3 Apr 2007 14:14:10 +0200 Received: from [80.229.56.224] (helo=beast.local) by pih-relay05.plus.net with esmtp (Exim) id 1HYhtm-0004UH-GX for caml-list@inria.fr; Tue, 03 Apr 2007 13:14:06 +0100 From: Jon Harrop Organization: Flying Frog Consultancy Ltd. To: caml-list Subject: Re: [Caml-list] How important are circular lists/recursive objects? Date: Tue, 3 Apr 2007 13:09:07 +0100 User-Agent: KMail/1.9.5 References: <4611FBAB.1020508@fmf.uni-lj.si> In-Reply-To: <4611FBAB.1020508@fmf.uni-lj.si> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-2" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200704031309.08302.jon@ffconsultancy.com> X-Miltered: at concorde with ID 46124511.001 by Joe's j-chkmail (http://j-chkmail . ensmp . fr)! X-Spam: no; 0.00; recursive:01 andrej:01 recursive:01 ocaml:01 vars:01 vars:01 ocaml:01 frog:98 closures:01 closures:01 wrote:01 wrote:01 rec:01 caml-list:01 functions:01 On Tuesday 03 April 2007 08:00, Andrej Bauer wrote: > Brian Hurt wrote: > > Does anyone actually use this construct, and if so, for what? > > When I teach my students "theory" of programming languages, we write > interpreters for mini languages. The recursive data structures are used > to create closures of recursive functions, environments that contain > mutually recursive values, closures of objects, etc. Life would be very > hard without this feature. There is a nice example here: http://www.ffconsultancy.com/ocaml/benefits/interpreter.html Specifically, in the "eval" function: | ELetRec(var, arg, body, rest) -> let rec vars = (var, VClosure(arg, vars, body)) :: vars in eval vars rest -- Dr Jon D Harrop, Flying Frog Consultancy Ltd. OCaml for Scientists http://www.ffconsultancy.com/products/ocaml_for_scientists