From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Original-To: caml-list@sympa.inria.fr Delivered-To: caml-list@sympa.inria.fr Received: from mail3-relais-sop.national.inria.fr (mail3-relais-sop.national.inria.fr [192.134.164.104]) by sympa.inria.fr (Postfix) with ESMTPS id 6C9387EE25 for ; Sun, 27 Oct 2013 13:16:20 +0100 (CET) Received-SPF: None (mail3-smtp-sop.national.inria.fr: no sender authenticity information available from domain of rossberg@mpi-sws.org) identity=pra; client-ip=139.19.1.49; receiver=mail3-smtp-sop.national.inria.fr; envelope-from="rossberg@mpi-sws.org"; x-sender="rossberg@mpi-sws.org"; x-conformance=sidf_compatible Received-SPF: Pass (mail3-smtp-sop.national.inria.fr: domain of rossberg@mpi-sws.org designates 139.19.1.49 as permitted sender) identity=mailfrom; client-ip=139.19.1.49; receiver=mail3-smtp-sop.national.inria.fr; envelope-from="rossberg@mpi-sws.org"; x-sender="rossberg@mpi-sws.org"; x-conformance=sidf_compatible; x-record-type="v=spf1" Received-SPF: None (mail3-smtp-sop.national.inria.fr: no sender authenticity information available from domain of postmaster@hera.mpi-klsb.mpg.de) identity=helo; client-ip=139.19.1.49; receiver=mail3-smtp-sop.national.inria.fr; envelope-from="rossberg@mpi-sws.org"; x-sender="postmaster@hera.mpi-klsb.mpg.de"; x-conformance=sidf_compatible X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AowDAN0CbVKLEwExhGdsb2JhbABZrlCUIoEyDgEBAQoHBAkJFCiCJQEBBAFAAQE3AQQLCw4KLlcGE4gBBgSkXIRTAQWOKQaPIjMHgx+BDa07 X-IPAS-Result: AowDAN0CbVKLEwExhGdsb2JhbABZrlCUIoEyDgEBAQoHBAkJFCiCJQEBBAFAAQE3AQQLCw4KLlcGE4gBBgSkXIRTAQWOKQaPIjMHgx+BDa07 X-IronPort-AV: E=Sophos;i="4.93,580,1378850400"; d="scan'208";a="32074258" Received: from infao0809.mpi-klsb.mpg.de (HELO hera.mpi-klsb.mpg.de) ([139.19.1.49]) by mail3-smtp-sop.national.inria.fr with ESMTP/TLS/AES256-SHA; 27 Oct 2013 13:16:20 +0100 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mpi-sws.org; s=mail200803; h=To:References:Message-Id:Content-Transfer-Encoding:Cc:Date:In-Reply-To:From:Content-Type:Mime-Version:Subject; bh=3MUB49SQY/Ft8sSPz5AwYmWuytTBJwxAwwEo7A2ZRGg=; b=qpr8Qpps50sUBPHH7N+5TSdLiZWbgLd74dLpyruqdqnRbksvc/N6NpAfmybiDPZKlq4kxkA0TJGGywKf74C1koIT2AkrTWMj6Z/l7qbOf5ciYCXQJb0P2y8vJs283n2taBaA454kkYUO32RUBySi2gaopFifvXtk84/ZQvUEKdk=; Received: from zak.mpi-klsb.mpg.de ([139.19.1.29]:48362) by hera.mpi-klsb.mpg.de (envelope-from ) with esmtp (Exim 4.72) id 1VaPGS-0003qH-Tu; Sun, 27 Oct 2013 13:16:19 +0100 Received: from mnch-5d856b49.pool.mediaways.net ([93.133.107.73]:54404 helo=[192.168.178.44]) by zak.mpi-klsb.mpg.de (envelope-from ) with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.72) id 1VaPGS-00070h-GH; Sun, 27 Oct 2013 13:16:16 +0100 Mime-Version: 1.0 (Mac OS X Mail 6.6 \(1510\)) Content-Type: text/plain; charset=iso-8859-1 From: Andreas Rossberg In-Reply-To: Date: Sun, 27 Oct 2013 13:16:14 +0100 Cc: OCaML List Mailing Content-Transfer-Encoding: quoted-printable Message-Id: <66AB5484-8BFC-4A1C-ADAC-99C75716B054@mpi-sws.org> References: <97627FCD-30E1-45AD-A72B-CD423170C0AC@math.nagoya-u.ac.jp> <20131025082911.GB23798@voyager> <878uxhd62p.fsf@golf.niidar.ru> <526A7F33.6040203@mpi-sws.org> To: Yaron Minsky X-Mailer: Apple Mail (2.1510) X-MPI-Local-Sender: true Subject: Re: [Caml-list] Equality between abstract type definitions On Oct 25, 2013, at 22:32 , Yaron Minsky wrote: > Changing the semantics of this will, I think, break a _lot_ of code. Interesting. Do you have specific examples in mind? > For what it's worth, I suspect that most people who are surprised by > this are people who were trained on Standard ML. At Jane Street we've > had a lot of people learn the language, and the complaints I've heard > about this feature are, I think, mostly from that group. Maybe, but it's not my impression that this is true for most people I see a= sking related questions here on the list or on SO. > I also don't find Andreas suggestion particularly intuitive. I would > have guessed that (x: '_a) would constrain x to be a weakly > polymorphic value, which is at odds with the proposal. Now, _that_ is something I would only expect from programmers trained on SM= L -- ancient SML'90 to be precise. ;) Note how OCaml already uses '_a for a sort of flexible variable in its outp= ut. /Andreas