From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Carl Witty Newsgroups: gmane.lisp.guile.devel Subject: Re: Text collation Date: Tue, 05 Dec 2006 10:42:01 -0800 Message-ID: <1165344122.21448.138.camel@meteor.newtonlabs.com> References: <877j00cirs.fsf@laas.fr> <87hcz3mqhr.fsf@zip.com.au> <87r6x0qjyy.fsf@laas.fr> <87fyc1df70.fsf@zip.com.au> <87zma9m07p.fsf@laas.fr> <87u00e6jxa.fsf@zip.com.au> <87fybwhw5a.fsf@laas.fr> <87slfvkxbc.fsf@zip.com.au> NNTP-Posting-Host: dough.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Trace: sea.gmane.org 1165344199 23721 80.91.229.10 (5 Dec 2006 18:43:19 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Tue, 5 Dec 2006 18:43:19 +0000 (UTC) Cc: Guile-Devel Original-X-From: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Tue Dec 05 19:43:18 2006 Return-path: Envelope-to: guile-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by dough.gmane.org with esmtp (Exim 4.50) id 1GrfG0-0006BZ-VP for guile-devel@m.gmane.org; Tue, 05 Dec 2006 19:43:09 +0100 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1GrfG0-0005vo-Cu for guile-devel@m.gmane.org; Tue, 05 Dec 2006 13:43:08 -0500 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1GrfFy-0005vh-Hc for guile-devel@gnu.org; Tue, 05 Dec 2006 13:43:06 -0500 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1GrfFv-0005vH-F0 for guile-devel@gnu.org; Tue, 05 Dec 2006 13:43:06 -0500 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1GrfFv-0005vE-CD for guile-devel@gnu.org; Tue, 05 Dec 2006 13:43:03 -0500 Original-Received: from [216.254.24.28] (helo=gemini.newtonlabs.com) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_3DES_EDE_CBC_SHA:24) (Exim 4.52) id 1GrfFv-0001HC-4Z for guile-devel@gnu.org; Tue, 05 Dec 2006 13:43:03 -0500 Original-Received: from meteor.newtonlabs.com (cwitty@meteor.newtonlabs.com [10.0.0.25]) by gemini.newtonlabs.com (8.12.3/8.12.3/Debian-7.1) with ESMTP id kB5Igo7T004470; Tue, 5 Dec 2006 10:42:59 -0800 Original-To: Kevin Ryde In-Reply-To: <87slfvkxbc.fsf@zip.com.au> X-Mailer: Evolution 2.6.3 X-MIME-Autoconverted: from 8bit to quoted-printable by gemini.newtonlabs.com id kB5Igo7T004470 X-BeenThere: guile-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Developers list for Guile, the GNU extensibility library" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Errors-To: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.lisp.guile.devel:6292 Archived-At: On Tue, 2006-12-05 at 11:20 +1100, Kevin Ryde wrote: > ludovic.courtes@laas.fr (Ludovic Court=E8s) writes: > > I don't clearly understand. Could you provide more details for the > > novice (perhaps in another thread)? :-) >=20 > The note in the manual: >=20 > *Caution*: The current code in this module incorrectly extends > the Gregorian calendar leap year rule back prior to the > introduction of those reforms in 1582 (or the appropriate year > in various countries). The Julian calendar was used prior to > 1582, and there were 10 days skipped for the reform, but the > code doesn't implement that. >=20 > So for instance the year 1500 should be a leap year, but isn't in the > current code. (If I've got that right off the top of my head ... :-) If I understand correctly, this would make date->julian-day (for instance) convert from Julian calendar dates before 1582 and Gregorian calendar dates after 1582. This is cute, but I don't think it's particularly useful; the problem is that the Julian to Gregorian switch lasted for hundreds of years around the world (and, indeed, some churches still use the Julian calendar to determine religious dates), so you can't tell if a date is Julian or Gregorian just by looking at the year. I would propose leaving the code the way it is now, and changing the note to something like "Note: Dates in this module use the proleptic Gregorian calendar, which means that it extends the Gregorian calendar leap year rule back prior to the introduction of these reforms in 1582." (See http://en.wikipedia.org/wiki/Proleptic_Gregorian_calendar for more information on the proleptic Gregorian calendar.) If people need to use Julian dates, then there should be a separate julian-date type with separate converters. Carl Witty _______________________________________________ Guile-devel mailing list Guile-devel@gnu.org http://lists.gnu.org/mailman/listinfo/guile-devel