>From: "Alan Lovejoy" <squeak-dev.sourcery at forum-mail.net>
>Reply-To: The general-purpose Squeak developers 
>list<squeak-dev at lists.squeakfoundation.org>
>To: "'The general-purpose Squeak developers 
>list'"<squeak-dev at lists.squeakfoundation.org>
>Subject: RE: [ANN] ICal occurrence API
>Date: Mon, 28 May 2007 12:54:48 -0700
>
>I fully intend to have a look at your code--after I've completed my
>implementation.  However, I don't plan on implementing a parser for
>iCal--the only goal is to be able to specify/represent (and fully and
>correctly implement) the iCal rule model.

I didn't either.  The iCalendar package made by Philippe does all that, it 
just didn't do anything with the recurrence rules once made.

>  Actually, the Chronos recurrence
>rule model goes beyond what can be specified using the iCal rule
>model/notation.  Using an algebra enables support for logical negation and
>disjunction, among other things (consider what Chalten does with its
>TimeLineFilter, for example.)

That sounds cool.  I went for the Recurrence rule standard which is ugly, 
ambiguous and, though my test coverage didn't point anything out, I think 
even self-contradicting.

I don't know anything about recurrence rule algebra but it sounds good. :)

>I'm also working on full support for business date arithmetic. I intend to
>meet or exceed the capabilities offered by jFin
>(http://jfin.org/date_adjustment) or ObjectLab
>(http://objectlabkit.sourceforge.net/), and to use the data provided by
>FinancialCalendar.com (http://financialcalendar.com/).

Very cool.

>As for "thunder stealing," that goes with the territory when two or more
>projects are in the same functional domain.  My goal is to implement the
>world's best date/time library in any language--and I've been working hard
>at it since October 2004.  I feel I've already achieved parity with 
>anything
>else out there.  Now it's time to go to the next level.

I wasn't mad or anything.  Just joking because of the timing of it. :)  But 
yes, now that you point it out, it would make more sense that the recurrence 
calculation code be with a time library, whether you use anything of mine or 
not.  I learned a lot in the doing.

>But, since my main motivation for making Chronos the best date/time library
>in the world is to help promote Smalltalk, I actually welcome any and all
>contributions by others to that goal.  And based on the description, your
>iCal engine certainly seems to be a worthy contribution.

Thanks.  I don't know how much of my stuff will be usable for you.  I got 
the approach from Haskell.  Basically the strategy is that the frequency 
creates an infinite list of "periods" which are the same thing as a TimeSpan 
but with a different interface.  All constraints (e.g. BYDAY) are applied to 
the period stream they get, and they generate the next period stream from 
it.  Once you get through all the constraints you should have the dates.

>Working together, we can leave Smalltalk's competition in the dust.  And
>inspire those working on Smalltalk projects in domains other than
>dates/times to do the same.
>
>Go Smalltalk!
>
>--Alan

That is what I want as well. :)

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