From 57322e766a0ece579dafcddcfe2572676a98fca8 Mon Sep 17 00:00:00 2001
From: Lukasz Kasprzak <lukas@labunix.xyz>
Date: Tue, 11 Aug 2026 11:37:32 +0200
Subject: 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.
---
 lib/kernel/date_spec.ml | 53 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 lib/kernel/date_spec.ml

(limited to 'lib/kernel/date_spec.ml')

diff --git a/lib/kernel/date_spec.ml b/lib/kernel/date_spec.ml
new file mode 100644
index 0000000..1d0da00
--- /dev/null
+++ b/lib/kernel/date_spec.ml
@@ -0,0 +1,53 @@
+(* How a sanctoral entry expresses its date. Plan 2 ships the only form the EF
+   sanctoral needs -- a fixed calendar date -- because EF movable feasts come
+   from the rite's temporal code, not from data. Sunday-relative and
+   Easter-relative forms arrive with the OF sanctoral. *)
+type t = Fixed of { month : int; day : int }
+
+(* Leap-year maximum, so 29 February is constructible; it simply does not
+   resolve in a common year. *)
+let max_day = function
+  | 1 | 3 | 5 | 7 | 8 | 10 | 12 -> 31
+  | 4 | 6 | 9 | 11 -> 30
+  | 2 -> 29
+  | _ -> 0
+
+let fixed ~month ~day =
+  if month < 1 || month > 12 then Error (Printf.sprintf "date_spec: month %d out of range 1..12" month)
+  else if day < 1 || day > max_day month then
+    Error (Printf.sprintf "date_spec: day %d out of range for month %d" day month)
+  else Ok (Fixed { month; day })
+
+let resolve t ~year =
+  match t with
+  | Fixed { month; day } -> Result.to_option (Date.make ~year ~month ~day)
+
+let sexp_of_t = function
+  | Fixed { month; day } ->
+      Sexplib0.Sexp.List [
+        Sexplib0.Sexp_conv.sexp_of_string "Fixed";
+        Sexplib0.Sexp.List [
+          Sexplib0.Sexp.List [
+            Sexplib0.Sexp_conv.sexp_of_string "month";
+            Sexplib0.Sexp_conv.sexp_of_int month
+          ];
+          Sexplib0.Sexp.List [
+            Sexplib0.Sexp_conv.sexp_of_string "day";
+            Sexplib0.Sexp_conv.sexp_of_int day
+          ]
+        ]
+      ]
+
+let t_of_sexp sexp =
+  match sexp with
+  | Sexplib0.Sexp.List [
+      Sexplib0.Sexp.Atom "Fixed";
+      Sexplib0.Sexp.List [
+        Sexplib0.Sexp.List [ Sexplib0.Sexp.Atom "month"; month_sexp ];
+        Sexplib0.Sexp.List [ Sexplib0.Sexp.Atom "day"; day_sexp ]
+      ]
+    ] ->
+      let month = Sexplib0.Sexp_conv.int_of_sexp month_sexp in
+      let day = Sexplib0.Sexp_conv.int_of_sexp day_sexp in
+      Fixed { month; day }
+  | _ -> Sexplib0.Sexp_conv.of_sexp_error "Date_spec.t_of_sexp: expected Fixed record format" sexp
-- 
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