TimezoneDetect

Exposes utilities derived from the excellent ZoneDetect library https://github.com/BertoldVdb/ZoneDetect. To use this module, you need to obtain database files from the aforementioned library's server.

Currently, only one function for looking up the name of a Timezone is provided, but the underlying library also has richer functions for opening timezone database files, finding applicable zones, etc.

Documentation

type TimezoneName = String

Alias for clarity, timezones are short strings that follow the IANA conventions documented here: https://data.iana.org/time-zones/tz-link.html

lookupTimezone :: FilePath -> Float -> Float -> Either String TimezoneName

Given a timezone database, latitude and longitude, try to determine the timezone name. Follow the instructions in the C library's repository to obtain timezone database files (https://github.com/BertoldVdb/ZoneDetect/tree/05567e367576d7f3efa00083b7661a01e43dc8ca/database) Once in possesion of said files, the lookup looks as follows:

>>> lookupTimezone "./test/tz_db/timezone21.bin" 40.7831 (-73.9712)
Right "America/New_York"

Failure conditions are: invalid database file, or invalid coordinates, both are returned as Left values.