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 XAA15196; Thu, 15 Jul 2004 23:17:21 +0200 (MET DST) X-Authentication-Warning: pauillac.inria.fr: majordomo set sender to owner-caml-list@pauillac.inria.fr using -f Received: from nez-perce.inria.fr (nez-perce.inria.fr [192.93.2.78]) by pauillac.inria.fr (8.7.6/8.7.3) with ESMTP id XAA14856 for ; Thu, 15 Jul 2004 23:17:20 +0200 (MET DST) Received: from smtp3.adl2.internode.on.net (smtp3.adl2.internode.on.net [203.16.214.203]) by nez-perce.inria.fr (8.12.10/8.12.10) with ESMTP id i6FLHHEV016995 for ; Thu, 15 Jul 2004 23:17:18 +0200 Received: from [192.168.1.200] (ppp216-145.lns1.syd3.internode.on.net [203.122.216.145]) by smtp3.adl2.internode.on.net (8.12.9/8.12.9) with ESMTP id i6FLHBHY015796; Fri, 16 Jul 2004 06:47:12 +0930 (CST) Subject: Re: [Caml-list] Unboxing options, was RE: assertions or exceptions? From: skaller Reply-To: skaller@users.sourceforge.net To: John Prevost Cc: Brian Hurt , Ocaml Mailing List In-Reply-To: References: Content-Type: text/plain Message-Id: <1089926230.29648.632.camel@pelican.wigram> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.2 (1.2.2-4) Date: 16 Jul 2004 07:17:10 +1000 Content-Transfer-Encoding: 7bit X-Miltered: at nez-perce with ID 40F6F45D.001 by Joe's j-chkmail (http://j-chkmail.ensmp.fr)! X-Loop: caml-list@inria.fr X-Spam: no; 0.00; caml-list:01 unboxing:01 sourceforge:01 2004:99 prevost:01 2004:99 cdt:99 boxing:01 unboxing:01 unboxed:01 runtime:01 9660:01 glebe:01 ocaml:01 null:01 Sender: owner-caml-list@pauillac.inria.fr Precedence: bulk On Fri, 2004-07-16 at 03:20, John Prevost wrote: > On Thu, 15 Jul 2004 10:38:14 -0500 (CDT), Brian Hurt wrote: > > One of the problems with returning error conditions instead of throwing > > exceptions is the cost of boxing a 'a option. I'd like to advocate for > > the idea of unboxing 'a options. > > This has been discussed before. The essential problem is this: > > Currently: > > type 'a option is not the same as type 'a option option > Some Some 1 is not the same as Some 1 > Some None is not the same as None > > With unboxed options: > > type 'a option is the same as type 'a option option > Some Some 1 is identical to Some 1 > Some None is identical to None This is wrong. The representation being suggested is: None -> NULL Some 'a -> pointer to 'a Clearly this represntation is faithful and nothing more than an interpretation of the corresponding C concept. Some Some 1 is obviously distinct from Some 1 as reqiuired: pointer to pointer to 1 is distinct from pointer to 1. Some None is a pointer to NULL, which is distinct from None which is just NULL. Perhaps this won't work with the Ocaml runtime but there is no problem with the typing. -- John Skaller, mailto:skaller@users.sf.net voice: 061-2-9660-0850, snail: PO BOX 401 Glebe NSW 2037 Australia Checkout the Felix programming language http://felix.sf.net ------------------- 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