From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (from majordomo@localhost) by pauillac.inria.fr (8.7.6/8.7.3) id DAA12187; Sun, 28 Jul 2002 03:46:42 +0200 (MET DST) X-Authentication-Warning: pauillac.inria.fr: majordomo set sender to owner-caml-list@pauillac.inria.fr using -f Received: from concorde.inria.fr (concorde.inria.fr [192.93.2.39]) by pauillac.inria.fr (8.7.6/8.7.3) with ESMTP id DAA12349 for ; Sun, 28 Jul 2002 03:46:41 +0200 (MET DST) Received: from sunny.pacific.net.au (sunny.pacific.net.au [203.25.148.40]) by concorde.inria.fr (8.11.1/8.11.1) with ESMTP id g6S1jmD13129 for ; Sun, 28 Jul 2002 03:45:55 +0200 (MET DST) Received: from wisma.pacific.net.au (wisma.pacific.net.au [210.23.129.72]) by sunny.pacific.net.au with ESMTP id g6S1jeSs028688; Sun, 28 Jul 2002 11:45:40 +1000 (EST) Received: from ozemail.com.au (ppp136.dyn17.pacific.net.au [61.8.17.136]) by wisma.pacific.net.au with ESMTP id LAA10510; Sun, 28 Jul 2002 11:45:38 +1000 (EST) Message-ID: <3D434CC3.6030508@ozemail.com.au> Date: Sun, 28 Jul 2002 11:45:39 +1000 From: John Max Skaller User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.2.1) Gecko/20010901 X-Accept-Language: en-us MIME-Version: 1.0 To: Alain Frisch CC: caml-list@inria.fr Subject: Re: [Caml-list] equi-recursive Fold isomorphism References: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-caml-list@pauillac.inria.fr Precedence: bulk Alain Frisch wrote: >My Recursive module uses the same technique; it may do what you want: >http://www.eleves.ens.fr:8080/home/frisch/soft#recursive > Thanks! Hmmm: Ocaml 3.04+15 with -rectypes # let rec x = (1,(1,(1,x)));; val x : int * (int * (int * 'a)) as 'a = .... Seem like Ocaml doesn't minimise the type, but: let rec y = (1,y);; x = y;; Works correctly (so it knows the two types are comparable). Interestingly, the answer is false: both data structures consist of an infinite stream of 1's, represented by cycles of distinct lengths. No item by item comparison could reveal any distinction: the infinite tree expansions of the data structures are the same. Is Ocaml's answer correct? -- John Max Skaller, mailto:skaller@ozemail.com.au snail:10/1 Toxteth Rd, Glebe, NSW 2037, Australia. voice:61-2-9660-0850 ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners