[Haskell-cafe] ANN: Bugfix release for timezone-olson

Yitzchak Gale gale at sefer.org
Wed Aug 25 17:41:19 EDT 2010

Version 0.1.1 of the timezone-olson package is now
available on Hackage.


The timezone-olson package provides a parser and renderer
for binary Olson timezone files whose format is specified
by the tzfile(5) man page on Unix-like systems. These files
are often found in /usr/share/zoneinfo on Unix-like systems.
Functions are provided for converting the parsed data into
TimeZoneSeries objects from the timezone-series package.

Now that "Version 2 format" Olson files are beginning to
appear in the wild, we can see the full details of how the
specification in the tzfile(5) man page is applied in real
life. This release fixes several bugs related to parsing
and rendering Version 2 format Olson files, as well as
a few other small issues. Updating is recommended.

A new version of the timezone-series package, also
version 0.1.1, is also now available on Hackage.


The timezone-series package endows Data.Time, from the
time package, with several data types and functions for
enhanced processing of timezones. Among them is
TimeZoneSeries,which represents all of the clock settings
that occur in a time zone, and functions to convert
between UTCTime and LocalTime without knowing in
advance what clock setting is in effect at the given moment.

This release of timezone-series only adds a few type
signatures and more documentation for isValidLocalTime
and isRedundantLocalTime and friends. Aristid Breitkreuz
provided a proof for the basic fact about time change
gaps and overlaps that is used to implement them.
The proof can be seen here:


Many thanks to Aristid who, in addition to providing
the above proof, assisted in finding bugs and preparing
for the release of these two updates.


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