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=none autolearn=disabled version=3.1.3 Received: from mail1-relais-roc.national.inria.fr (mail1-relais-roc.national.inria.fr [192.134.164.82]) by yquem.inria.fr (Postfix) with ESMTP id A6FE2BC6B for ; Thu, 10 Jan 2008 16:07:49 +0100 (CET) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AgAAAJ7DhUfAXQInh2dsb2JhbACQHwEBAQgKKYEUmB8 X-IronPort-AV: E=Sophos;i="4.24,267,1196636400"; d="scan'208";a="6499343" Received: from concorde.inria.fr ([192.93.2.39]) by mail1-smtp-roc.national.inria.fr with ESMTP; 10 Jan 2008 16:07:49 +0100 Received: from mail3-relais-sop.national.inria.fr (mail3-relais-sop.national.inria.fr [192.134.164.104]) by concorde.inria.fr (8.13.6/8.13.6) with ESMTP id m0AF7m6w030323 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=OK) for ; Thu, 10 Jan 2008 16:07:49 +0100 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AgAAAJ7DhUfBL1AZk2dsb2JhbACQHwEBAQEHCgkggRSYHw X-IronPort-AV: E=Sophos;i="4.24,267,1196636400"; d="scan'208";a="7644703" Received: from gw.exalead.com (HELO exalead.com) ([193.47.80.25]) by mail3-smtp-sop.national.inria.fr with ESMTP; 10 Jan 2008 16:07:46 +0100 Received: from [192.168.204.148] (madpc064.exalead.com [192.168.204.148]) (authenticated bits=0) by exalead.com (8.14.0/8.14.0) with ESMTP id m0AF7h9F005881; Thu, 10 Jan 2008 16:07:45 +0100 Message-ID: <478634BF.7010805@exalead.com> Date: Thu, 10 Jan 2008 16:07:43 +0100 From: Berke Durak User-Agent: Thunderbird 1.5.0.10 (X11/20070221) MIME-Version: 1.0 To: Thomas Fischbacher Cc: Caml-list List Subject: Re: [Caml-list] Annoying behaviour of OCaml References: <4786312A.1050003@functionality.de> In-Reply-To: <4786312A.1050003@functionality.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Miltered: at concorde with ID 478634C4.000 by Joe's j-chkmail (http://j-chkmail . ensmp . fr)! X-Spam: no; 0.00; berke:01 durak:01 berke:01 durak:01 ocaml:01 ocaml:01 arrays:01 recursive:01 arrays:01 ocaml's:01 caml-list:01 surprising:01 strings:01 behaviour:01 behaviour:01 Thomas Fischbacher a écrit : > > Yesterday, we were bitten quite badly by a rude surprise where OCaml > behaved in a rather different way from what we would have expected: Surprising. I didn't notice before that arrays are compared hierarchically and not lexicographically. > I think it would be a *very* good idea to provide > compare_lexicographically in addition to compare as a pre-defined built-in, > as this is (1) what many people want to do, (2) it cannot be implemented > without resorting to either C or black magic, and (3) it would not change > the behaviour of already existing code that uses "compare". Lexicographic order is quite natural for recursive sum types such as lists. As for arrays, I guess the intent was to accelerate cases where the array lengths are different. Assume you are sorting a random array of arrays of random lengths, but whose contents have large common prefixes. You'll have to do more work to sort these with lexicographical ordering. OTOH this reasoning would also apply to strings which are compared lexicographically... Ocaml's ways are mysterious! However I don't think it's worth cluttering the standard library with compare_lexicographically as it can be easily implemented. -- Berke DURAK