diff --git a/xo-procedure2/include/xo/procedure2/DPrimitive.hpp b/xo-procedure2/include/xo/procedure2/DPrimitive.hpp
index 7735bf0b..4cc45f83 100644
--- a/xo-procedure2/include/xo/procedure2/DPrimitive.hpp
+++ b/xo-procedure2/include/xo/procedure2/DPrimitive.hpp
@@ -6,6 +6,7 @@
 #pragma once
 
 #include "RuntimeContext.hpp"
+#include <xo/type/Type.hpp>
 #include <xo/object2/DArray.hpp>
 #include <xo/alloc2/GCObjectConversion.hpp>
 #include <xo/alloc2/GCObject.hpp>
@@ -152,7 +153,12 @@ namespace xo {
             /** name of this primitive **/
             std::string_view name_;
 
-            /** type description for function
+            /** primitive type-constructor. These are non-trivial to establish;
+             *  not convenient to establish in ctor
+             **/
+            obj<AType> type_;
+
+            /** type description for implementation function
              *  Note that this type description will have additional first argument
              *  for obj<ARuntimeContext>
              **/
diff --git a/xo-type/include/xo/type/Metatype.hpp b/xo-type/include/xo/type/Metatype.hpp
index 6fc193ae..30952df8 100644
--- a/xo-type/include/xo/type/Metatype.hpp
+++ b/xo-type/include/xo/type/Metatype.hpp
@@ -40,6 +40,9 @@ namespace xo {
                 /* struct<a:T,b:U,..> */
                 t_struct,
 
+                /* any numeric type: i16|i32|i64|f32|f64 */
+                t_numeric,
+
                 /* any type at all */
                 t_any,
             };
@@ -64,6 +67,7 @@ namespace xo {
             static Metatype t_function() { return Metatype(code::t_function); }
             static Metatype t_struct()   { return Metatype(code::t_struct);   }
 
+            static Metatype t_numeric()  { return Metatype(code::t_numeric);  }
             static Metatype t_any()      { return Metatype(code::t_any);      }
 
             /** description string for this type category **/
diff --git a/xo-type/src/type/Metatype.cpp b/xo-type/src/type/Metatype.cpp
index ca61d9c9..9e50f11a 100644
--- a/xo-type/src/type/Metatype.cpp
+++ b/xo-type/src/type/Metatype.cpp
@@ -29,6 +29,7 @@ namespace xo {
             case code::t_function: return "function";
             case code::t_struct:   return "struct";
 
+            case code::t_numeric:  return "numeric";
             case code::t_any:      return "any";
             }
         }
@@ -68,6 +69,8 @@ namespace xo {
             case code::t_struct:
                 return false;
 
+            case code::t_numeric:
+                return true;
             case code::t_any:
                 return true;
             }