4 files changed, 11 insertions, 9 deletions
diff --git a/lib/kernel/Namespace.ml b/lib/kernel/Namespace.ml
index 7c9cd2b..20f83f5 100644
--- a/lib/kernel/Namespace.ml
+++ b/lib/kernel/Namespace.ml
@@ -38,12 +38,14 @@ class namespace = object (self)
   method list =
     Atomic.get entries
     |> BatMap.keys
-    |> BatList.of_enum
+    |> BatFingerTree.of_enum
+    |> Result.ok
 
   method find key =
     Atomic.get entries
     |> BatMap.find_opt key
     |> Utilities.Option.fmap Protocols.Handle.copy
+    |> Result.ok
 end
 
-let make () = new namespace
+let make () = Protocols.Handle.make (new namespace)
diff --git a/lib/kernel/Namespace.mli b/lib/kernel/Namespace.mli
index 3ed64a3..ec77724 100644
--- a/lib/kernel/Namespace.mli
+++ b/lib/kernel/Namespace.mli
@@ -4,4 +4,4 @@ class namespace : object
   inherit Protocols.Registry.implementation
 end
 
-val make : unit -> namespace
+val make : unit -> Protocols.Handle.t
diff --git a/lib/protocols/Directory.ml b/lib/protocols/Directory.ml
index 5b21668..0d2507e 100644
--- a/lib/protocols/Directory.ml
+++ b/lib/protocols/Directory.ml
@@ -1,6 +1,6 @@
 class type implementation = object
-  method list : string list
-  method find : string -> Handle.t option
+  method list : (string BatFingerTree.t, Concepts.Condition.condition) result
+  method find : string -> (Handle.t option, Concepts.Condition.condition) result
 end
 
 type Handle.protocol += Directory of implementation
diff --git a/lib/protocols/Directory.mli b/lib/protocols/Directory.mli
index 5bf5277..9033235 100644
--- a/lib/protocols/Directory.mli
+++ b/lib/protocols/Directory.mli
@@ -1,13 +1,13 @@
 type t
 
 class type implementation = object
-  method list : string list
-  method find : string -> Handle.t option
+  method list : (string BatFingerTree.t, Concepts.Condition.condition) result
+  method find : string -> (Handle.t option, Concepts.Condition.condition) result
 end
 
 val make : #implementation -> Handle.protocol
 
 val from : Handle.t -> t Handle.interface option
 
-val list : t Handle.interface -> string list
-val find : t Handle.interface -> string -> Handle.t option
+val list : t Handle.interface -> (string BatFingerTree.t, Concepts.Condition.condition) result
+val find : t Handle.interface -> string -> (Handle.t option, Concepts.Condition.condition) result