kernel: Vocab, Celebration and Temporal parametric types

Rite specificity is carried by type parameters plus a vocab record of
operations rather than by functors: the same guarantee that a rite cannot name
another rite's season, without threading module plumbing through every kernel
module. Celebration takes only the rank parameter, since it has no season
field and OCaml rejects a type variable that appears in no field.

1 files changed, 19 insertions, 0 deletions

diff --git a/lib/kernel/vocab.mli b/lib/kernel/vocab.mli
new file mode 100644
index 0000000..78729bb
--- /dev/null
+++ b/lib/kernel/vocab.mli
@@ -0,0 +1,19 @@
+(* A rite's season and rank vocabulary, as a record of operations. Carries
+   functions, so it has no sexp form.
+
+   The kernel is parameterised by type variables plus this record rather than by
+   functors (spec §2.3): the safety that matters -- EF code cannot name an OF
+   season -- is the same either way, and ppx_sexp_conv derives converters for
+   parametric types natively. *)
+type ('s, 'r) t = {
+  seasons : 's list;
+      (** canonical liturgical-year order; Validate's contiguity check reads this *)
+  season_to_string : 's -> string;
+  season_of_string : string -> 's option;
+  ranks : 'r list;
+      (** documentation order, highest first. Plan 2 uses it only for the
+          closure check -- it is not a precedence relation until Plan 3
+          defines one. *)
+  rank_to_string : 'r -> string;
+  rank_of_string : string -> 'r option;
+}