To convert Gregorian to Jalali:
to_jalali (Date 2017 6 25)
To convert Jalali to Gregorian:
to_gregorian (Date 1395 4 20)
More examples:
import Html exposing (text)
today = Date 2017 6 25
main =
[ to_jalali today
, to_gregorian {year=1396, month=04, day=04}
] |> toString
|> text