From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail2-relais-roc.national.inria.fr (mail2-relais-roc.national.inria.fr [192.134.164.83]) by sympa.inria.fr (Postfix) with ESMTPS id B2184E0128 for ; Wed, 31 Aug 2022 10:25:23 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=inria.fr; s=dc; h=subject:to:cc:references:from:message-id:date: mime-version:in-reply-to:content-transfer-encoding; bh=Lg2dZMrKp7uqZKR3hGJ0h6Xq2+npY0fwch/l9R2kopM=; b=Vf9CcdScPPBikm0HzROjnk5cyb0AQY8ceuIuvF+4FDCcZfmyVjuj83V2 +5NxOUP0+aVRdqSJUFCW+dApYJgsVACO22PXJWNVDc/ixds0XiECg7MyJ K6zPYy7mqvvc2AyDO+WJc/88InDnWbCVXHvUAJs3JYv6EoQTe1CgGQ//t I=; Authentication-Results: mail2-relais-roc.national.inria.fr; dkim=none (message not signed) header.i=none; spf=SoftFail smtp.mailfrom=francois.pottier@inria.fr; dmarc=fail (p=none dis=none) d=inria.fr X-IronPort-AV: E=Sophos;i="5.93,277,1654552800"; d="scan'208";a="50647834" Received: from 91-175-127-215.subs.proxad.net (HELO MacBook-Pro-5.local) ([91.175.127.215]) by mail2-relais-roc.national.inria.fr with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2022 10:25:23 +0200 To: Andreas Rossberg Cc: caml-list@inria.fr References: <25e68e2c-04d2-7764-e189-00812c08a34a@inria.fr> <8078ad33-f220-b233-4863-06ce30cc8cff@inria.fr> <2C890C66-F8F7-402C-B88E-587C3E21DE89@mpi-sws.org> From: =?UTF-8?Q?Fran=c3=a7ois_Pottier?= Message-ID: <99c919e0-95aa-2c4f-7240-71486da1fb65@inria.fr> Date: Wed, 31 Aug 2022 10:25:23 +0200 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: <2C890C66-F8F7-402C-B88E-587C3E21DE89@mpi-sws.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Subject: Re: [Caml-list] coinductive data types Hi Andreas, Le 30/08/2022 à 18:45, Andreas Rossberg a écrit : > I’m curious why you would categorise iso-recursive types as nominal. I have always considered them structural as well, since two structurally matching iso-recursive type expressions are still deemed equivalent. I had in mind a system with algebraic data types, which have a name, and where two algebraic data types with distinct names can never be related by subtyping. In such a system, an algebraic data type is *not* equal to its unfolding, which is why I used the word "iso-recursive". It is quite possible that I used the wrong word, and should not have referred to such types as "iso-recursive". -- François Pottier francois.pottier@inria.fr http://cambium.inria.fr/~fpottier/