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 mail1-relais-roc.national.inria.fr (mail1-relais-roc.national.inria.fr [192.134.164.82]) by yquem.inria.fr (Postfix) with ESMTP id F3CDCBBAF for ; Mon, 26 May 2008 14:35:50 +0200 (CEST) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AqgBANBLOkjAXQIniGdsb2JhbACSOwEBAQ8gmTI X-IronPort-AV: E=Sophos;i="4.27,542,1204498800"; d="scan'208";a="12719597" Received: from concorde.inria.fr ([192.93.2.39]) by mail1-smtp-roc.national.inria.fr with ESMTP; 26 May 2008 14:35:50 +0200 Received: from mail4-relais-sop.national.inria.fr (mail4-relais-sop.national.inria.fr [192.134.164.105]) by concorde.inria.fr (8.13.6/8.13.6) with ESMTP id m4QCZi7V004494 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=OK) for ; Mon, 26 May 2008 14:35:50 +0200 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AlAAABdLOkiBrw8Eo2dsb2JhbACSOwEBAQEBCAUIBxGZLw X-IronPort-AV: E=Sophos;i="4.27,542,1204498800"; d="scan'208";a="26611260" Received: from ext.lri.fr ([129.175.15.4]) by mail4-smtp-sop.national.inria.fr with ESMTP; 26 May 2008 14:35:50 +0200 Received: from localhost (localhost [127.0.0.1]) by ext.lri.fr (Postfix) with ESMTP id 5676AA47E1; Mon, 26 May 2008 14:35:50 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at lri.fr Received: from ext.lri.fr ([127.0.0.1]) by localhost (ext.lri.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id G+xwqayZJG3i; Mon, 26 May 2008 14:35:50 +0200 (CEST) Received: from smtp.lri.fr (vhost3-23 [129.175.3.23]) by ext.lri.fr (Postfix) with ESMTP id 3EBD1A4285; Mon, 26 May 2008 14:35:50 +0200 (CEST) Received: from [129.175.4.107] (lri4-107 [129.175.4.107]) by smtp.lri.fr (Postfix) with ESMTP id 3A60DE04FD; Mon, 26 May 2008 14:35:50 +0200 (CEST) Message-ID: <483AAF0C.7060500@lri.fr> Date: Mon, 26 May 2008 14:37:32 +0200 From: Romain Bardou User-Agent: Thunderbird 2.0.0.14 (X11/20080505) MIME-Version: 1.0 To: Richard Jones Cc: caml-list@inria.fr Subject: Re: [Caml-list] Question about type unification References: <20080526122204.GA6727@annexia.org> In-Reply-To: <20080526122204.GA6727@annexia.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Miltered: at concorde with ID 483AAEA0.001 by Joe's j-chkmail (http://j-chkmail . ensmp . fr)! X-Spam: no; 0.00; lri:01 unification:01 unification:01 abbreviation:01 unifying:01 3.0:98 opaque:01 caml-list:01 string:02 string:02 module:03 float:03 float:03 unit:03 guess:04 Richard Jones a écrit : > With this definition: > > type 'a t = float > > Why is this allowed? > > # ((3.0 : unit t) : string t) ;; > - : string t = 3. > > Note that unification is prevented if t is opaque, eg, hidden behind a > module signature. > > Rich. > My guess is that 'a t being just a type abbreviation, it is expanded to float when unifying. Private types are not type abbreviations, so they can't be expanded. -- Romain Bardou