(** A scripture *reference* (e.g. ["Jn 3:16"]), never scripture text. *)
type part = First | Psalm | Second | Gospel | Tract | Alleluia | Sequence
[@@deriving sexp]

val all_parts : part list
val part_to_string : part -> string
val part_of_string : string -> part option

type t = { part : part; reference : string } [@@deriving sexp]

val sexp_of_t : t -> Sexplib0.Sexp.t
val t_of_sexp : Sexplib0.Sexp.t -> t