1 files changed, 45 insertions, 0 deletions
diff --git a/ocaml/test/test_op9.ml b/ocaml/test/test_op9.ml
new file mode 100644
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+++ b/ocaml/test/test_op9.ml
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+(* Test opcode 9 (invoke) *)
+
+open Nock_lib
+
+let () =
+  (* Build a simple core: [[formula] payload] *)
+  (* Formula at slot 2: [0 3] (returns payload) *)
+  (* Payload at slot 3: 42 *)
+  let core = Noun.cell
+    (Noun.cell (Noun.atom 0) (Noun.atom 3))
+    (Noun.atom 42)
+  in
+
+  (* Test: *[core [9 2 [0 1]]] *)
+  (* This should:
+     1. Evaluate [0 1] on core → core
+     2. Extract slot 2 from core → [0 3]
+     3. Evaluate [0 3] on core → 42
+  *)
+
+  let subject = core in
+  let formula = Noun.cell
+    (Noun.atom 9)
+    (Noun.cell
+      (Noun.atom 2)
+      (Noun.cell (Noun.atom 0) (Noun.atom 1)))
+  in
+
+  Printf.printf "Subject (core): [[0 3] 42]\n";
+  Printf.printf "Subject mug: 0x%08lx\n" (Noun.mug subject);
+  Printf.printf "Formula: [9 2 [0 1]]\n";
+  Printf.printf "Formula mug: 0x%08lx\n\n" (Noun.mug formula);
+
+  Printf.printf "This should compute:\n";
+  Printf.printf "  1. Evaluate [0 1] on core → core\n";
+  Printf.printf "  2. Extract slot 2 from result → [0 3]\n";
+  Printf.printf "  3. Evaluate [0 3] on core → 42\n\n";
+
+  let result = Nock.nock_on subject formula in
+
+  Printf.printf "Result mug: 0x%08lx\n" (Noun.mug result);
+  Printf.printf "Result: %s\n"
+    (match result with
+     | Noun.Atom { z; _ } -> Z.to_string z
+     | Noun.Cell _ -> "cell")