(** 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] exactly when the date falls outside every numbered week the
          rite defines (e.g. a season with no week numbering at all, or a
          transitional span between two numbered runs). A day being *named*
          is not by itself a reason for [None]: a named day that sits inside
          a numbered season run must carry that run's week the same as any
          other day in it. *)
  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