xo-interpreter: vsm work on environments [WIP]

include/xo/interpreter2/DGlobalEnv.hpp

@@ -0,0 +1,29 @@
+/** @file DGlobalEnv.hpp
+ *
+ *  @author Roland Conybeare, Feb 2026
+ **/
+
+#pragma once
+
+#include <xo/expression2/DGlobalSymtab.hpp>
+#include <xo/object2/DList.hpp>
+
+namespace xo {
+    namespace scm {
+
+
+        /** @brief runtime bindings for global variabels
+         **/
+        class DGlobalEnv {
+        public:
+            DGLobalEnv() = default;
+
+        private:
+            // absurd O(n) implementation for now
+            // replace with gc-aware hashtable, when available.
+
+            /** globals.  Slots in @ref global_v_ are numbered in DLocalSymtab **/
+            DArray * global_v_ = nullptr;
+        };
+    }
+}

include/xo/interpreter2/DLocalEnv.hpp

@@ -11,7 +11,7 @@
 namespace xo {
     namespace scm {
 
-        /** @brief bindings for arguments to a lambda
+        /** @brief runtime bindings for arguments to a lambda
          **/
         class DLocalEnv {
         public:

include/xo/interpreter2/DVsmRcx.hpp

@@ -0,0 +1,2 @@
+/** @file DVsmRcx.hpp
+n*

include/xo/interpreter2/VirtualSchematikaMachine.hpp

@@ -194,6 +194,9 @@ namespace xo {
             // for VM stack. Only works for code that doesn't rely on fancy
             // lexical scoping
 
+            // consider separate allocator for reader (i.e. program code)
+            // and data (program execution)
+
             /** reader: text -> expression **/
             SchematikaReader reader_;
 
@@ -206,6 +209,16 @@ namespace xo {
             /** expression register **/
             obj<AExpression> expr_;
 
+            /** environment pointer.  Provides bindings
+             *  for surrounding lexical scope at this point
+             *  in execution
+             **/
+            DLocalEnv * local_env_ = nullptr;
+            /** environment pointer.  Maintains bindings
+             *  for global variables.
+             **/
+            DGlobalEnv * global_env_ = nullptr;
+
             /** function to call **/
             obj<AProcedure> fn_;
             /** evaluated argument list **/