Immutable associative collection protocol

1 files changed, 16 insertions, 0 deletions

diff --git a/lib/protocols/Associative.ml b/lib/protocols/Associative.ml
new file mode 100644
index 0000000..aa691d0
--- /dev/null
+++ b/lib/protocols/Associative.ml
@@ -0,0 +1,16 @@
+class type implementation = object
+  method update : string -> Handle.t option -> Handle.t option -> (Handle.t, Concepts.Condition.condition) result
+end
+
+type Handle.protocol += Associative of implementation
+
+type t = implementation
+
+let make impl = Associative (impl :> implementation)
+
+let from handle = Handle.into handle (function Associative impl -> Some impl | _ -> None)
+
+let update i key reference value = Handle.invoke i (fun o ->
+                                       let open Utilities.Result in
+                                       let* h = o#update key reference value in
+                                       Handle.require from h)