(** The temporal identity of a date: where in the liturgical year it sits, and
    the temporal cycle's own office for it. *)
type ('s, 'r) t = {
  season : 's;
  week : int option;  (** [None] for named days outside a numbered week *)
  weekday : Date.weekday;
  office : 'r Celebration.t;
}
[@@deriving sexp]

module type RITE = sig
  val id : string

  type season
  type rank

  val vocab : (season, rank) Vocab.t

  (** First day of the liturgical year opening in civil year [y]. *)
  val year_start : int -> Date.t

  (** Total over 1583..9999: every date yields exactly one temporal identity. *)
  val temporal : Date.t -> (season, rank) t
end