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 LAA20256; Tue, 27 Aug 2002 11:59:33 +0200 (MET DST) X-Authentication-Warning: pauillac.inria.fr: majordomo set sender to owner-caml-list@pauillac.inria.fr using -f Received: from nez-perce.inria.fr (nez-perce.inria.fr [192.93.2.78]) by pauillac.inria.fr (8.7.6/8.7.3) with ESMTP id LAA20202 for ; Tue, 27 Aug 2002 11:59:32 +0200 (MET DST) Received: from postfix2-2.free.fr (postfix2-2.free.fr [213.228.0.140]) by nez-perce.inria.fr (8.11.1/8.11.1) with ESMTP id g7R9xVn27229; Tue, 27 Aug 2002 11:59:31 +0200 (MET DST) Received: from imp1-1.pro.proxad.net (imp1-1.pro.proxad.net [212.27.35.86]) by postfix2-2.free.fr (Postfix) with ESMTP id E1A9E5F757; Tue, 27 Aug 2002 11:59:30 +0200 (CEST) Received: by imp1-1.pro.proxad.net (Postfix, from userid 33) id C3D6578202; Tue, 27 Aug 2002 11:59:30 +0200 (MEST) To: Xavier Leroy Subject: Re: [Caml-list] Hashtbl.hash and Hashtbl.hash_param Message-ID: <1030442366.3d6b4d7eb7db1@imp.pro.proxad.net> Date: Tue, 27 Aug 2002 11:59:26 +0200 (MEST) From: jeanmarc.eber@lexifi.com Cc: sebastien FURIC , caml-list@inria.fr References: <3D6653C0.F895EC59@tni.fr> <20020827102435.A17823@pauillac.inria.fr> In-Reply-To: <20020827102435.A17823@pauillac.inria.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit User-Agent: IMP/PHP IMAP webmail program 2.2.42 X-Originating-IP: 207.45.248.21 Sender: owner-caml-list@pauillac.inria.fr Precedence: bulk Quoting Xavier Leroy : > > However, we need to think twice before changing the hashing function, > because this would cause trouble to users that store hashtables in > files using output_value/input_value: if the hash function changes > before writing and reading, the hashtable read becomes unusable. > > Hence, a request for OCaml users: if you use hashtables whose keys are > structured data (not just strings or integers), *and* your program > stores hashtables to files, *and* it's important for you that these > persistent hashtables can be read back with future versions of OCaml, > then please drop me a line. > That is an important point that should, I think, at least be clearly said. Personally, I always thought that values written with output_value (more generally marshaled ocaml values) were only guaranteed to be compatible for a given version of ocaml. I never considered output_value as a "long term" storing solution, but only a "short term" one (good example: *.cmo ans *.cmi files generated by the ocaml compiler), not to speak about calculated hash values... Personally, I *want* the ocaml team to be able to change internal representation, optimize hash functions etc in the hope that this produces an even better system! (BTW, I may be wrong, but didn’t some tags change between 3.04 and 3.05, but maybe this didn’t change marshaled values ?) More generally, the concept and importance of 100% backward compatibility should be discussed. I can not hope for 100% backward compatibility and hope for big progresses on the ocaml compiler... no ? If people really want 100% compatibilty, they should stay with an ocaml version. Conclusion: personally, I don’t want progress of the compiler made difficult by a 100% backward compatibility "religion". What do other users of ocaml think about it? (I agree that this is of course a question that is as old as the existence of computer languages: its more a question about what stage of development we think ocaml has reached now) Jean-Marc Eber LexiFi ------------------- 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