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=3.0 required=5.0 tests=AWL,DNS_FROM_RFC_ABUSE, DNS_FROM_RFC_POST,NO_REAL_NAME,SPF_NEUTRAL autolearn=disabled version=3.1.3 Received: from mail2-relais-roc.national.inria.fr (mail2-relais-roc.national.inria.fr [192.134.164.83]) by yquem.inria.fr (Postfix) with ESMTP id C7B0CBC69 for ; Fri, 5 Oct 2007 18:46:44 +0200 (CEST) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AgAAAJ4HBkfAXQImh2dsb2JhbACOOQIBCAop X-IronPort-AV: E=Sophos;i="4.21,236,1188770400"; d="scan'208";a="2428910" Received: from discorde.inria.fr ([192.93.2.38]) by mail2-smtp-roc.national.inria.fr with ESMTP; 05 Oct 2007 18:46:44 +0200 Received: from mail1-relais-roc.national.inria.fr (mail1-relais-roc.national.inria.fr [192.134.164.82]) by discorde.inria.fr (8.13.6/8.13.6) with ESMTP id l95GkiOQ025017 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=OK) for ; Fri, 5 Oct 2007 18:46:44 +0200 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AgAAAA8HBkfOLvwqlmdsb2JhbACOOQIBAQcEBhERBw X-IronPort-AV: E=Sophos;i="4.21,236,1188770400"; d="scan'208";a="2196261" Received: from vms042pub.verizon.net ([206.46.252.42]) by mail1-smtp-roc.national.inria.fr with ESMTP; 05 Oct 2007 18:46:43 +0200 Received: from vms064.mailsrvcs.net ([192.168.1.2]) by vms042.mailsrvcs.net (Sun Java System Messaging Server 6.2-6.01 (built Apr 3 2006)) with ESMTPA id <0JPG00D356GJK6I0@vms042.mailsrvcs.net> for caml-list@inria.fr; Fri, 05 Oct 2007 11:43:34 -0500 (CDT) Received: from 66.212.151.230 ([66.212.151.230]) by vms064.mailsrvcs.net (Verizon Webmail) with HTTP; Fri, 05 Oct 2007 11:43:31 -0500 (CDT) Date: Fri, 05 Oct 2007 11:43:31 -0500 (CDT) From: Subject: Re: Re: [Caml-list] Depend-type beginner question X-Originating-IP: [66.212.151.230] To: caml-list@inria.fr Message-id: <17047747.21961991191602611279.JavaMail.root@vms064.mailsrvcs.net> MIME-version: 1.0 Content-type: text/plain; charset=UTF-8 Content-transfer-encoding: 7bit X-Miltered: at discorde with ID 47066A74.001 by Joe's j-chkmail (http://j-chkmail . ensmp . fr)! X-Spam: no; 0.00; verizon:98 syntactic:01 caml-list:01 cons:04 distinguish:05 nil:06 i'm:09 theory:09 internally:11 beginner:12 question:13 between:13 type:14 type:14 but:14 > > The type system is not rich enough to distinguish between 0-lists' > > and 1-list's. It is just a list. > > So what is the gain ? I'm not sure about the actual implementation, but in theory a list is something like: type 'a list = Nil | Cons of 'a * 'a list [] and [a] and h :: t are just syntactic sugar. So lists don't even know their own length internally, unlike an array.