From 42b5cc7aea2af85e7c7fc54d0def4f68bfa96b0a Mon Sep 17 00:00:00 2001
From: Roland Conybeare <rconybeare@gmail.com>
Date: Sun, 15 Mar 2026 14:35:44 -0500
Subject: [PATCH] xo-interpreter2 stack: move fn_n_args() to ObjectPrimitives

---
 include/xo/procedure2/ObjectPrimitives.hpp    |  4 ++++
 src/procedure2/ObjectPrimitives.cpp           | 24 +++++++++++++++++++
 .../procedure2_register_primitives.cpp        |  1 +
 3 files changed, 29 insertions(+)

diff --git a/include/xo/procedure2/ObjectPrimitives.hpp b/include/xo/procedure2/ObjectPrimitives.hpp
index ee2dfae..1de2fd2 100644
--- a/include/xo/procedure2/ObjectPrimitives.hpp
+++ b/include/xo/procedure2/ObjectPrimitives.hpp
@@ -6,6 +6,7 @@
 #pragma once
 
 #include "Primitive_gco_0.hpp"
+#include "Primitive_gco_1_gco.hpp"
 #include "Primitive_gco_2_gco_gco.hpp"
 #include "Primitive_gco_3_dict_string_gco.hpp"
 
@@ -35,6 +36,9 @@ namespace xo {
 
             /** create primitive that upserts a key,value pair into a dictionary **/
             static DPrimitive_gco_3_dict_string_gco * make_dict_upsert_pm(obj<AAllocator> mm);
+
+            /** create primitive: get fixed number of args for function **/
+            static DPrimitive_gco_1_gco * make_fn_n_args_pm(obj<AAllocator> mm);
         };
 
     } /*namespace scm*/
diff --git a/src/procedure2/ObjectPrimitives.cpp b/src/procedure2/ObjectPrimitives.cpp
index f5d7ab1..29e9e9b 100644
--- a/src/procedure2/ObjectPrimitives.cpp
+++ b/src/procedure2/ObjectPrimitives.cpp
@@ -133,6 +133,30 @@ namespace xo {
             return DPrimitive_gco_3_dict_string_gco::_make(mm, "dict_upsert", &xfer_dict_upsert);
         }
 
+        // ----- fn_n_args -----
+
+        obj<AGCObject>
+        xfer_fn_n_args(obj<ARuntimeContext> rcx,
+                       obj<AGCObject> fn_gco)
+        {
+            scope log(XO_DEBUG(true));
+
+            log && log(xtag("fn_gco.tseq", fn_gco._typeseq()));
+            log && log(xtag("fn_gco.tname", TypeRegistry::id2name(fn_gco._typeseq())));
+
+            auto fn_proc = FacetRegistry::instance().try_variant<AProcedure,AGCObject>(fn_gco);
+
+            assert(fn_proc);
+
+            return DInteger::box<AGCObject>(rcx.allocator(), fn_proc.n_args());
+        }
+
+        DPrimitive_gco_1_gco *
+        ObjectPrimitives::make_fn_n_args_pm(obj<AAllocator> mm)
+        {
+            return DPrimitive_gco_1_gco::_make(mm, "fn_n_args", &xfer_fn_n_args);
+        }
+
     } /*namespace scm*/
 } /*namespace xo*/
 
diff --git a/src/procedure2/procedure2_register_primitives.cpp b/src/procedure2/procedure2_register_primitives.cpp
index a5502d6..2585457 100644
--- a/src/procedure2/procedure2_register_primitives.cpp
+++ b/src/procedure2/procedure2_register_primitives.cpp
@@ -66,6 +66,7 @@ namespace xo {
             ok = ok & install_aux(sink, ObjectPrimitives::make_cons_pm(mm), flags);
             ok = ok & install_aux(sink, ObjectPrimitives::make_dict_make_pm(mm), flags);
             ok = ok & install_aux(sink, ObjectPrimitives::make_dict_upsert_pm(mm), flags);
+            ok = ok & install_aux(sink, ObjectPrimitives::make_fn_n_args_pm(mm), flags);
 
             return ok;
         }