xo-interpreter: add Primitive object, to expose builtin functions

xo-interpreter/src/interpreter/BuiltinPrimitives.cpp

@@ -0,0 +1,39 @@
+/** @file BuiltinPrimitives.cpp
+ *
+ *  @author Roland Conybeare, Nov 2025
+ **/
+
+#include "BuiltinPrimitives.hpp"
+#include "ObjectConversion.hpp"
+#include "Integer.hpp"
+#include "Primitive.hpp"
+#include "xo/reflect/Reflect.hpp"
+#include <cstdint>
+
+namespace xo {
+    using xo::reflect::Reflect;
+    using xo::reflect::TypeDescr;
+
+    namespace scm {
+        int64_t
+        add64(int64_t x, int64_t y)
+        {
+            return x + y;
+        }
+
+        void
+        BuiltinPrimitives::install(gc::IAlloc * mm, gp<GlobalEnv> env)
+        {
+            {
+                gp<Object> rhs = xo::obj::make_primitive(mm, add64);
+                TypeDescr td = Reflect::require<decltype(add64)>();
+                rp<Variable> lhs = Variable::make("add", td);
+                gp<Object> * addr = env->establish_var(lhs.borrow());
+
+                *addr = rhs;
+            }
+        }
+    }
+}
+
+/* end BuiltinPrimitives.cpp */