kernel: Colour and Subject shared vocabulary

The six liturgical colours and the Lord/BVM/saint/temporal distinction are
common to both Roman forms, so they are shared closed variants rather than
rite-parametric. Subject is so named because class is an OCaml keyword.

4 files changed, 39 insertions, 0 deletions

diff --git a/lib/kernel/colour.ml b/lib/kernel/colour.ml
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+++ b/lib/kernel/colour.ml
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+(* Liturgical colours. Shared across Roman rites (spec §2.1): not
+   rite-parametric, because EF and OF use the same six. *)
+type t = White | Red | Green | Violet | Rose | Black [@@deriving sexp]
+
+let all = [ White; Red; Green; Violet; Rose; Black ]
+
+let to_string = function
+  | White -> "white" | Red -> "red" | Green -> "green"
+  | Violet -> "violet" | Rose -> "rose" | Black -> "black"
+
+let of_string = function
+  | "white" -> Some White | "red" -> Some Red | "green" -> Some Green
+  | "violet" -> Some Violet | "rose" -> Some Rose | "black" -> Some Black
+  | _ -> None
diff --git a/lib/kernel/colour.mli b/lib/kernel/colour.mli
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+++ b/lib/kernel/colour.mli
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+(** Liturgical colours, shared by all Roman rites. *)
+type t = White | Red | Green | Violet | Rose | Black [@@deriving sexp]
+
+val all : t list
+val to_string : t -> string
+val of_string : string -> t option
diff --git a/lib/kernel/subject.ml b/lib/kernel/subject.ml
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+++ b/lib/kernel/subject.ml
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+(* Whom the celebration is of. Named [Subject] rather than [Class] because
+   [class] is an OCaml keyword. Used by precedence in Plan 3 (RG 91). *)
+type t = Temporal | Saint | Bvm | Lord [@@deriving sexp]
+
+let all = [ Temporal; Saint; Bvm; Lord ]
+
+let to_string = function
+  | Temporal -> "temporal" | Saint -> "saint" | Bvm -> "bvm" | Lord -> "lord"
+
+let of_string = function
+  | "temporal" -> Some Temporal | "saint" -> Some Saint
+  | "bvm" -> Some Bvm | "lord" -> Some Lord
+  | _ -> None
diff --git a/lib/kernel/subject.mli b/lib/kernel/subject.mli
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+++ b/lib/kernel/subject.mli
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+(** Whom a celebration is of. [Temporal] is the temporal cycle's own office. *)
+type t = Temporal | Saint | Bvm | Lord [@@deriving sexp]
+
+val all : t list
+val to_string : t -> string
+val of_string : string -> t option