1 files changed, 53 insertions, 14 deletions
diff --git a/lib/kernel/Initialization.ml b/lib/kernel/Initialization.ml
index 3c8addb..518fe4f 100644
--- a/lib/kernel/Initialization.ml
+++ b/lib/kernel/Initialization.ml
@@ -1,23 +1,62 @@
+module Error = struct
+  open Concepts.Condition
+
+  let taken name =
+    condition "name-taken" "A namespace already binds the name"
+      ("name" |=| Concepts.Value.String name)
+end
+
+let bind namespace (name, handle) =
+  let open Utilities.Result in
+  let* registry = Protocols.Handle.require Protocols.Registry.from namespace in
+  let* bound = Protocols.Registry.update registry name None (Some handle) in
+  if bound then Ok () else Error (Error.taken name)
+
+let namespace entries =
+  let into = Namespace.make () in
+  let open Utilities.Result in
+  let* () =
+    List.fold_left
+      (fun acc entry ->
+        let* () = acc in
+        bind into entry )
+      (Ok ()) entries
+  in
+  Ok into
+
+(* A subsystem's root holds what is its own and not data: its
+   evaluators, and whatever else it registers beside them. *)
+let mount root name =
+  match Path.lookup root Path.(name @/ this) with
+  | Ok mounted -> Ok mounted
+  | Error _ ->
+      let open Utilities.Result in
+      let* mounted = namespace ["evaluator", Namespace.make ()] in
+      let* () = bind root (name, mounted) in
+      Ok mounted
+
 module Make (S : Abstract.Storage.STORAGE) = struct
   module BM = BranchManager.Make (S)
+  module B = Branch.Make (S)
 
+  (* The heads of \system's branches, of which there is always a master,
+     are kept under the label rnt-head. *)
   let initialize ?(evaluators = []) conn =
     let open Utilities.Result in
-    let open Protocols in
     let root = Namespace.make () in
-    let registry = Registry.from root |> Option.get in
-    let* branch_manager = BM.make conn "rnt-head" in
-    let* _ = Registry.update registry "branch" None (Some branch_manager) in
-    let evaluator_namespace = Namespace.make () in
-    let evaluator_registry = Registry.from evaluator_namespace |> Option.get in
-    let* _ =
-      List.fold_left
-        (fun acc (name, handle) ->
-          let* _ = acc in
-          Registry.update evaluator_registry name None (Some handle) )
-        (Ok true) evaluators
+    let* evaluator = namespace evaluators in
+    let* branch = BM.make ~root conn "rnt-head" in
+    let* () =
+      if Path.lookup branch Path.("master" @/ this) |> Result.is_ok then Ok ()
+      else Result.bind (B.make conn) (fun empty -> bind branch ("master", empty))
+    in
+    let* system =
+      namespace
+        [ "branch", branch;
+          "evaluator", evaluator;
+          "session", Namespace.make ();
+          "application", Namespace.make () ]
     in
-    let* _ = Registry.update registry "evaluator" None (Some evaluator_namespace) in
-    let* _ = Registry.update registry "session" None (Some (Namespace.make ())) in
+    let* () = bind root ("system", system) in
     Ok root
 end