Add optional time to dates

[cblp]

Probable solution:

-- | Day and Maybe Time
type DMT = Either Day UTCTime

Day is treated in current time zone, UTCTime is UTC

With timezone

use a string. Specifically, use the full qualified name in the Olson database, so something like Australia/Adelaide or America/Los_Angeles. These are standardized descriptors of the timezones used in the world, and you can use these in pretty much every programming language ever used in the last few decades.

https://en.wikipedia.org/wiki/List_of_tz_database_time_zones

https://zachholman.com/talk/utc-is-enough-for-everyone-right