Hygiene: Expose ListStorageType

Capnp.MessageSig.S is public (aka. part of wrapped capnp.ml), and has a ListStorage module.

But ListStorage.t has a storage_type field of type 'Capnp.MessageSig.ListStorageType.t' that is not public.

This commit makes ListStorageType public.

src/runtime/capnp.ml

@@ -37,6 +37,7 @@ module Array        = CArray
 module BytesStorage = BytesStorage
 module BytesMessage = Message.BytesMessage
 module Codecs       = Codecs
+module ListStorageType = ListStorageType
 module RPC          = RPC
 module Runtime = struct
   module BuilderInc      = BuilderInc

src/runtime/listStorageType.ml

@@ -3,23 +3,13 @@ let sizeof_uint64 = 8
 
 type t =
   | Empty
-  (** list(void), no storage required *)
-
   | Bit
-  (** list(bool), tightly packed bits *)
-
   | Bytes1
   | Bytes2
   | Bytes4
   | Bytes8
-  (** either primitive values or a data-only struct *)
-
   | Pointer
-  (** either a pointer to an external object, or a pointer-only struct *)
-
   | Composite of int * int
-  (** typical struct; parameters are per-element word size for data section
-      and pointers section, respectively *)
 
 let get_byte_count storage_type =
   match storage_type with

src/runtime/listStorageType.mli

@@ -0,0 +1,23 @@
+(** @canonical Capnp.ListStorageType  *)
+
+type t =
+  | Empty
+  (** list(void), no storage required *)
+
+  | Bit
+  (** list(bool), tightly packed bits *)
+
+  | Bytes1
+  | Bytes2
+  | Bytes4
+  | Bytes8
+  (** either primitive values or a data-only struct *)
+
+  | Pointer
+  (** either a pointer to an external object, or a pointer-only struct *)
+
+  | Composite of int * int
+  (** typical struct; parameters are per-element word size for data section
+      and pointers section, respectively *)
+
+val get_byte_count : t -> int