Fri, 20 Jun 2003 19:16:43 +0100
Home historical timezone offsets are sub-minutes -- there's mention of an
example in RFC3339, at the end of section 5.8:
This represents the same instant of time as noon, January 1, 1937,
Netherlands time. Standard time in the Netherlands was exactly 19
minutes and 32.13 seconds ahead of UTC by law from 1909-05-01 through
1937-06-30. This time zone cannot be represented exactly using the
HH:MM format, and this timestamp uses the closest representable UTC
Which leads mew to mention a slight unease about including time zone name
information in the library . Have you seen how many different time zone
names there can be? Many with different rules for daylight savings time,
etc. This is one of the things we chopped in producing RFC3339 from the
My own feeling that it may be OK to have a facility to add a time zone name
(or abstract structure) to a clocktime, in addition to a timezone offset,
but I'm uneasy about having a built-in method that works it out for
you. Maybe, then, an external library function can be provided to do the
name-to-offset mapping (hmmm... sounds like a possible semantic web
application to me ;-) Doing offset-to-name mapping would be even more
difficult, because of non-uniqueness.
 From Simon's recent proposal:
-- | Make a 'Timezone' from an offset, in minutes relative to UTC,
-- which must be less than @24*60@.
timezoneFromOffset :: Int -> Timezone
-- | Make a 'Timezone' from a standard timezone name (eg. GMT, PDT).
-- TAI is a valid timezone name.
timezoneFromName :: String -> Timezone
-- | Return the offset in minutes of the specified timezone relative
-- to UTC.
timezoneOffset :: Timezone -> Int
-- | Return the timezone name corresponding to a 'Timezone' value.
timezoneName :: Timezone -> String
At 17:14 20/06/03 +0100, Keith Wansbrough wrote:
> > - Timezone offsets are in minutes (apparently this is necessary -
> > if someone could provide a reference I'd be grateful).
>Keith Wansbrough <firstname.lastname@example.org>
>University of Cambridge Computer Laboratory.
>Libraries mailing list
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