Hello, you basically need to implement the Calendar behaviour. There’s a similar project called jalaali and the calendar implementation is here: elixir-jalaali/lib/jalaali/calendar.ex at main · jalaali/elixir-jalaali · GitHub. There’s also a simple calendar used by Elixir tests here: https://github.com/elixir-lang/elixir/blob/master/lib/elixir/test/elixir/fixtures/calendar/holocene.exs.
