kernel: Names, Citation and Date_spec

Names is an open language-keyed assoc kept in canonical order so equal name
sets serialise identically. Citation carries references only, never text.
Date_spec ships the one form the EF sanctoral needs; 29 February is
constructible and resolves to None in common years.

1 files changed, 12 insertions, 0 deletions

diff --git a/lib/kernel/date_spec.mli b/lib/kernel/date_spec.mli
new file mode 100644
index 0000000..600f1eb
--- /dev/null
+++ b/lib/kernel/date_spec.mli
@@ -0,0 +1,12 @@
+(** A sanctoral entry's date expression. *)
+type t = Fixed of { month : int; day : int } [@@deriving sexp]
+
+val sexp_of_t : t -> Sexplib0.Sexp.t
+val t_of_sexp : Sexplib0.Sexp.t -> t
+
+(** Validates against the leap-year maximum, so 29 February is constructible. *)
+val fixed : month:int -> day:int -> (t, string) result
+
+(** [None] when the spec does not occur in that year (29 February in a common
+    year) or falls outside the supported domain. *)
+val resolve : t -> year:int -> Date.t option