[Haskell] ANNOUNCE: time-recurrence-0.1

Ashley Yakeley ashley at semantic.org
Sun May 22 01:30:41 CEST 2011

On 2011-05-18 12:45, Chris Heller wrote:

> The general direction is to have something that works much like the
> RRULE portion of
> the iCalendar (RFC 5545) specification. I have decided avoid strict
> RFC compliance at
> this time.

At one point I investigated a really generalised version of this, 
including an abstract syntax type and perhaps a way of parsing some 
useful subset of English expressions into it. However I got stuck on 
such things as

  "any day after the sixth Sunday of a month"

In order to prove that today was not such a day, it would have know that 
"sixth Sunday of a month" never happens. Simply searching into the past 
for one would never terminate. Either I would have to restrict the 
language, or assert the beginning of time (not necessarily a bad solution).

Anyway, a possible project for you or someone.

Ashley Yakeley

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