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 X-Original-To: caml-list@yquem.inria.fr Delivered-To: caml-list@yquem.inria.fr 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 BF9D4BB84 for ; Sat, 30 Aug 2008 13:38:37 +0200 (CEST) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: ApoEALzNuEjAXQIm/2dsb2JhbAC1J4Fp X-IronPort-AV: E=Sophos;i="4.32,296,1217800800"; d="scan'208";a="14402610" Received: from discorde.inria.fr ([192.93.2.38]) by mail2-smtp-roc.national.inria.fr with ESMTP; 30 Aug 2008 13:38:37 +0200 Received: from mail4-relais-sop.national.inria.fr (mail4-relais-sop.national.inria.fr [192.134.164.105]) by discorde.inria.fr (8.13.6/8.13.6) with ESMTP id m7UBcbg3025385 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=OK) for ; Sat, 30 Aug 2008 13:38:37 +0200 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Ai4BAPfNuEjUNQVbf2dsb2JhbACSRgEBCQcIBw6iNIFp X-IronPort-AV: E=Sophos;i="4.32,296,1217800800"; d="scan'208";a="28640409" Received: from postbode01.versateladsl.be ([212.53.5.91]) by mail4-smtp-sop.national.inria.fr with ESMTP/TLS/DHE-RSA-AES256-SHA; 30 Aug 2008 13:38:36 +0200 Received: (qmail 24834 invoked by uid 0); 30 Aug 2008 11:38:15 -0000 Received: from unknown (HELO poincare.swapping.umh.ac.be) ([83.182.222.100]) (envelope-sender ) by smtp.versateladsl.be (qmail-ldap-1.03) with SMTP for < >; 30 Aug 2008 11:38:15 -0000 Received: from [127.0.0.1] (helo=localhost ident=trch) by poincare.swapping.umh.ac.be with esmtp (Exim 4.69) (envelope-from ) id 1KZOml-0002xd-9R; Sat, 30 Aug 2008 13:38:31 +0200 Date: Sat, 30 Aug 2008 13:38:31 +0200 (CEST) Message-Id: <20080830.133831.122629365592826302.Christophe.Troestler+ocaml@umh.ac.be> To: Richard Jones Cc: OCaml Mailing List Subject: Re: [Caml-list] What does underscore mean in this type expression? From: Christophe TROESTLER In-Reply-To: <20080830112718.GA25303@annexia.org> References: <20080830112718.GA25303@annexia.org> X-Face: #2fb%mPx>rRL@4ff~TVgZ"<[:,oL"`TUEGK/[8/qb58~C>jR(x4A+v/n)7BgpEtIph_neoLKJBq0JBY9:}8v|j Organization: University of Mons-Hainaut X-Mailer: Mew version 6.0.51 on Emacs 22.2 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Miltered: at discorde with ID 48B9313D.000 by Joe's j-chkmail (http://j-chkmail . ensmp . fr)! X-Spam: no; 0.00; christophe:01 troestler:01 christophe:01 troestler:01 ocaml:01 0100,:01 val:01 val:01 syntax:01 cheers:01 wrote:01 caml-list:01 umh:01 expression:02 underscore:02 On Sat, 30 Aug 2008 12:27:18 +0100, Richard Jones wrote: > > val get_domains : > (_[> `R ] as 'a) Connect.t -> > is not included in > val get_domains : > ([> `R ] as 'a) Connect.t -> > > This syntax doesn't appear to be documented in the manual (unless it's > related to '_a). What does it mean? It is a weak type as you guessed. To convince you of that, here is some code: # let x = ref `X;; val x : _[> `X ] ref = {contents = `X} Cheers, C.