2 files changed, 34 insertions, 0 deletions
diff --git a/lib/backend/managers/Cursor.ml b/lib/backend/managers/Cursor.ml
new file mode 100644
index 0000000..3295cae
--- /dev/null
+++ b/lib/backend/managers/Cursor.ml
@@ -0,0 +1,18 @@
+type descriptor =
+  | Stored of {merkle_root: string}
+  | Ephemeral of {merkle_root: string; dependencies: string BatFingerTree.t}
+
+module Make (Store : Abstract.Storage.STORAGE) = struct
+  type cursor = unit
+
+  let open_ (_txn : Store.transaction) (descriptor : descriptor)
+      ~(args : Concepts.Value.value BatFingerTree.t) : (cursor, Concepts.Condition.condition) result
+      =
+    ignore (descriptor, args);
+    failwith "NOT IMPLEMENTED: open a cursor by paging the relation's Merkle tree over Store.get"
+
+  let next (_cursor : cursor) : (Concepts.Tuple.t option, Concepts.Condition.condition) result =
+    failwith "NOT IMPLEMENTED: page the next tuple over Store.get"
+
+  let close (_cursor : cursor) : unit = ()
+end
diff --git a/lib/backend/managers/Cursor.mli b/lib/backend/managers/Cursor.mli
new file mode 100644
index 0000000..71fb15d
--- /dev/null
+++ b/lib/backend/managers/Cursor.mli
@@ -0,0 +1,16 @@
+type descriptor =
+  | Stored of {merkle_root: string}
+  | Ephemeral of {merkle_root: string; dependencies: string BatFingerTree.t}
+
+module Make (Store : Abstract.Storage.STORAGE) : sig
+  type cursor
+
+  val open_ :
+    Store.transaction ->
+    descriptor ->
+    args:Concepts.Value.value BatFingerTree.t ->
+    (cursor, Concepts.Condition.condition) result
+
+  val next : cursor -> (Concepts.Tuple.t option, Concepts.Condition.condition) result
+  val close : cursor -> unit
+end