datatype day_of_week = Sunday | Monday | Tuesday | Wednesday | Thursday | Friday | Saturday datatype month = January | February | March | April | May | June | July | August | September | October | November | December type t = { Year : int, Month : month, Day : int, Hour : int, Minute : int, Second : int } val ord_datetime : ord t val show_day_of_week : show day_of_week val show_month : show month val eq_day_of_week : eq day_of_week val eq_month : eq month val dayOfWeekToInt : day_of_week -> int val intToDayOfWeek : int -> day_of_week val monthToInt : month -> int val intToMonth : int -> month val toTime : t -> time val fromTime : time -> t val format : string -> t -> string val dayOfWeek : t -> day_of_week val now : transaction t val normalize : t -> t val addSeconds : int -> t -> t val addMinutes : int -> t -> t val addHours : int -> t -> t val addDays : int -> t -> t