diff --git a/include/xo/interpreter2/DClosure.hpp b/include/xo/interpreter2/DClosure.hpp
index 4d24d72e..8472cfc5 100644
--- a/include/xo/interpreter2/DClosure.hpp
+++ b/include/xo/interpreter2/DClosure.hpp
@@ -19,7 +19,7 @@ namespace xo {
         class DClosure {
         public:
             using ARuntimeContext = xo::scm::ARuntimeContext;
-            using ACollector = xo::mm::ACollector;
+            //using ACollector = xo::mm::ACollector;
             using AGCObject = xo::mm::AGCObject;
             using AGCObjectVisitor = xo::mm::AGCObjectVisitor;
             using AAllocator = xo::mm::AAllocator;
@@ -58,7 +58,7 @@ namespace xo {
             /** @defgroup scm-closure-gcobject-facet **/
             ///@{
 
-            DClosure * shallow_move(obj<ACollector> gc) noexcept;
+            DClosure * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
             void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
 
             ///@}
diff --git a/include/xo/interpreter2/DLocalEnv.hpp b/include/xo/interpreter2/DLocalEnv.hpp
index 5270dec1..e60727b0 100644
--- a/include/xo/interpreter2/DLocalEnv.hpp
+++ b/include/xo/interpreter2/DLocalEnv.hpp
@@ -16,7 +16,7 @@ namespace xo {
         class DLocalEnv {
         public:
             using DArray = xo::scm::DArray;
-            using ACollector = xo::mm::ACollector;
+            //using ACollector = xo::mm::ACollector;
             using AGCObject = xo::mm::AGCObject;
             using AGCObjectVisitor = xo::mm::AGCObjectVisitor;
             using AAllocator = xo::mm::AAllocator;
@@ -55,7 +55,7 @@ namespace xo {
             /** @defgroup scm-localenv-gcobject-facet **/
             ///@{
 
-            DLocalEnv * shallow_move(obj<ACollector> gc) noexcept;
+            DLocalEnv * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
             void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
 
             ///@}
diff --git a/include/xo/interpreter2/DVsmApplyClosureFrame.hpp b/include/xo/interpreter2/DVsmApplyClosureFrame.hpp
index 8dd30efb..66cbf81a 100644
--- a/include/xo/interpreter2/DVsmApplyClosureFrame.hpp
+++ b/include/xo/interpreter2/DVsmApplyClosureFrame.hpp
@@ -41,7 +41,7 @@ namespace xo {
 
             /** gcobject facet **/
             std::size_t shallow_size() const noexcept;
-            DVsmApplyClosureFrame * shallow_move(obj<ACollector> gc) noexcept;
+            DVsmApplyClosureFrame * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
             void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
 
             /** pretty-printing support **/
diff --git a/include/xo/interpreter2/DVsmApplyFrame.hpp b/include/xo/interpreter2/DVsmApplyFrame.hpp
index d8e9ab79..60a572aa 100644
--- a/include/xo/interpreter2/DVsmApplyFrame.hpp
+++ b/include/xo/interpreter2/DVsmApplyFrame.hpp
@@ -14,7 +14,7 @@ namespace xo {
         class DVsmApplyFrame {
         public:
             using AProcedure = xo::scm::AProcedure;
-            using ACollector = xo::mm::ACollector;
+            //using ACollector = xo::mm::ACollector;
             using AGCObject = xo::mm::AGCObject;
             using AGCObjectVisitor = xo::mm::AGCObjectVisitor;
             using AAllocator = xo::mm::AAllocator;
@@ -38,7 +38,7 @@ namespace xo {
 
             void assign_fn(obj<AGCObject> x) { this->fn_ = x; }
 
-            DVsmApplyFrame * shallow_move(obj<ACollector> gc) noexcept;
+            DVsmApplyFrame * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
             void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
 
             /** pretty-printing support **/
diff --git a/include/xo/interpreter2/DVsmDefContFrame.hpp b/include/xo/interpreter2/DVsmDefContFrame.hpp
index acdd8a90..79a9227c 100644
--- a/include/xo/interpreter2/DVsmDefContFrame.hpp
+++ b/include/xo/interpreter2/DVsmDefContFrame.hpp
@@ -15,7 +15,7 @@ namespace xo {
          **/
         class DVsmDefContFrame {
         public:
-            using ACollector = xo::mm::ACollector;
+            //using ACollector = xo::mm::ACollector;
             using AGCObjectVisitor = xo::mm::AGCObjectVisitor;
             using AAllocator = xo::mm::AAllocator;
             using AGCObject = xo::mm::AGCObject;
@@ -51,7 +51,7 @@ namespace xo {
             /** @defgroup scm-vsmdefcontframe-gcobject-facet gcobject facet **/
             ///@{
 
-            DVsmDefContFrame * shallow_move(obj<ACollector> gc) noexcept;
+            DVsmDefContFrame * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
             void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
 
             ///@}
diff --git a/include/xo/interpreter2/DVsmEvalArgsFrame.hpp b/include/xo/interpreter2/DVsmEvalArgsFrame.hpp
index ab7a4607..34d74b9a 100644
--- a/include/xo/interpreter2/DVsmEvalArgsFrame.hpp
+++ b/include/xo/interpreter2/DVsmEvalArgsFrame.hpp
@@ -14,7 +14,7 @@ namespace xo {
         /** frame for executing an apply expression **/
         class DVsmEvalArgsFrame {
         public:
-            using ACollector = xo::mm::ACollector;
+            //using ACollector = xo::mm::ACollector;
             using AGCObject = xo::mm::AGCObject;
             using AGCObjectVisitor = xo::mm::AGCObjectVisitor;
             using AAllocator = xo::mm::AAllocator;
@@ -43,7 +43,7 @@ namespace xo {
 
             int32_t increment_arg() { return ++i_arg_; }
 
-            DVsmEvalArgsFrame * shallow_move(obj<ACollector> gc) noexcept;
+            DVsmEvalArgsFrame * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
             void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
 
             bool pretty(const ppindentinfo & ppii) const;
diff --git a/include/xo/interpreter2/DVsmIfElseContFrame.hpp b/include/xo/interpreter2/DVsmIfElseContFrame.hpp
index 82c5ee31..4d3176dc 100644
--- a/include/xo/interpreter2/DVsmIfElseContFrame.hpp
+++ b/include/xo/interpreter2/DVsmIfElseContFrame.hpp
@@ -15,7 +15,7 @@ namespace xo {
          **/
         class DVsmIfElseContFrame {
         public:
-            using ACollector = xo::mm::ACollector;
+            //using ACollector = xo::mm::ACollector;
             using AGCObjectVisitor = xo::mm::AGCObjectVisitor;
             using AGCObject = xo::mm::AGCObject;
             using AAllocator = xo::mm::AAllocator;
@@ -51,7 +51,7 @@ namespace xo {
             /** @defgroup scm-vsmevalsequenceframe-gcobject-facet gcobject facet **/
             ///@{
 
-            DVsmIfElseContFrame * shallow_move(obj<ACollector> gc) noexcept;
+            DVsmIfElseContFrame * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
             void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
 
             ///@}
diff --git a/include/xo/interpreter2/DVsmSeqContFrame.hpp b/include/xo/interpreter2/DVsmSeqContFrame.hpp
index 65532996..6b141cc6 100644
--- a/include/xo/interpreter2/DVsmSeqContFrame.hpp
+++ b/include/xo/interpreter2/DVsmSeqContFrame.hpp
@@ -15,7 +15,7 @@ namespace xo {
          **/
         class DVsmSeqContFrame {
         public:
-            using ACollector = xo::mm::ACollector;
+            //using ACollector = xo::mm::ACollector;
             using AAllocator = xo::mm::AAllocator;
             using AGCObject = xo::mm::AGCObject;
             using AGCObjectVisitor = xo::mm::AGCObjectVisitor;
@@ -32,10 +32,10 @@ namespace xo {
 
             /** create instance using memory from allocator @p mm **/
             static DVsmSeqContFrame * make(obj<AAllocator> mm,
-                                                obj<AGCObject> parent,
-                                                VsmInstr cont,
-                                                DSequenceExpr * seq_expr,
-                                                uint32_t i_seq);
+                                           obj<AGCObject> parent,
+                                           VsmInstr cont,
+                                           DSequenceExpr * seq_expr,
+                                           uint32_t i_seq);
 
             ///@}
             /** @defgroup scm-vsmevalsequenceframe-access-methods access methods **/
@@ -56,7 +56,7 @@ namespace xo {
             /** @defgroup scm-vsmevalsequenceframe-gcobject-facet gcobject facet **/
             ///@{
 
-            DVsmSeqContFrame * shallow_move(obj<ACollector> gc) noexcept;
+            DVsmSeqContFrame * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
             void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
 
             ///@}
diff --git a/include/xo/interpreter2/define/IGCObject_DVsmDefContFrame.hpp b/include/xo/interpreter2/define/IGCObject_DVsmDefContFrame.hpp
index 8c95cf65..215515ac 100644
--- a/include/xo/interpreter2/define/IGCObject_DVsmDefContFrame.hpp
+++ b/include/xo/interpreter2/define/IGCObject_DVsmDefContFrame.hpp
@@ -53,8 +53,9 @@ namespace xo {
             // const methods
 
             // non-const methods
-            /** move instance using collector **/
-            static Opaque shallow_move(DVsmDefContFrame & self, obj<ACollector> gc) noexcept;
+            /** move instance using object visitor.
+Arguably abusing the word 'visitor' here **/
+            static Opaque gco_shallow_move(DVsmDefContFrame & self, obj<AGCObjectVisitor> gc) noexcept;
             /** Invoke fn.visit_child(iface,data) for each child GCObject pointer.
 Context: provides address of data pointer so it can be updated in place
 when @p fn invokes garbage collector reentry point **/
diff --git a/include/xo/interpreter2/detail/IGCObject_DClosure.hpp b/include/xo/interpreter2/detail/IGCObject_DClosure.hpp
index a875406f..6e6058dd 100644
--- a/include/xo/interpreter2/detail/IGCObject_DClosure.hpp
+++ b/include/xo/interpreter2/detail/IGCObject_DClosure.hpp
@@ -53,8 +53,9 @@ namespace xo {
             // const methods
 
             // non-const methods
-            /** move instance using collector **/
-            static Opaque shallow_move(DClosure & self, obj<ACollector> gc) noexcept;
+            /** move instance using object visitor.
+Arguably abusing the word 'visitor' here **/
+            static Opaque gco_shallow_move(DClosure & self, obj<AGCObjectVisitor> gc) noexcept;
             /** Invoke fn.visit_child(iface,data) for each child GCObject pointer.
 Context: provides address of data pointer so it can be updated in place
 when @p fn invokes garbage collector reentry point **/
diff --git a/include/xo/interpreter2/detail/IGCObject_DVsmApplyClosureFrame.hpp b/include/xo/interpreter2/detail/IGCObject_DVsmApplyClosureFrame.hpp
index ec79f34e..9a021127 100644
--- a/include/xo/interpreter2/detail/IGCObject_DVsmApplyClosureFrame.hpp
+++ b/include/xo/interpreter2/detail/IGCObject_DVsmApplyClosureFrame.hpp
@@ -53,8 +53,9 @@ namespace xo {
             // const methods
 
             // non-const methods
-            /** move instance using collector **/
-            static Opaque shallow_move(DVsmApplyClosureFrame & self, obj<ACollector> gc) noexcept;
+            /** move instance using object visitor.
+Arguably abusing the word 'visitor' here **/
+            static Opaque gco_shallow_move(DVsmApplyClosureFrame & self, obj<AGCObjectVisitor> gc) noexcept;
             /** Invoke fn.visit_child(iface,data) for each child GCObject pointer.
 Context: provides address of data pointer so it can be updated in place
 when @p fn invokes garbage collector reentry point **/
diff --git a/include/xo/interpreter2/detail/IGCObject_DVsmApplyFrame.hpp b/include/xo/interpreter2/detail/IGCObject_DVsmApplyFrame.hpp
index da5dc97d..2936f81e 100644
--- a/include/xo/interpreter2/detail/IGCObject_DVsmApplyFrame.hpp
+++ b/include/xo/interpreter2/detail/IGCObject_DVsmApplyFrame.hpp
@@ -53,8 +53,9 @@ namespace xo {
             // const methods
 
             // non-const methods
-            /** move instance using collector **/
-            static Opaque shallow_move(DVsmApplyFrame & self, obj<ACollector> gc) noexcept;
+            /** move instance using object visitor.
+Arguably abusing the word 'visitor' here **/
+            static Opaque gco_shallow_move(DVsmApplyFrame & self, obj<AGCObjectVisitor> gc) noexcept;
             /** Invoke fn.visit_child(iface,data) for each child GCObject pointer.
 Context: provides address of data pointer so it can be updated in place
 when @p fn invokes garbage collector reentry point **/
diff --git a/include/xo/interpreter2/detail/IGCObject_DVsmEvalArgsFrame.hpp b/include/xo/interpreter2/detail/IGCObject_DVsmEvalArgsFrame.hpp
index d0faa515..15a09267 100644
--- a/include/xo/interpreter2/detail/IGCObject_DVsmEvalArgsFrame.hpp
+++ b/include/xo/interpreter2/detail/IGCObject_DVsmEvalArgsFrame.hpp
@@ -53,8 +53,9 @@ namespace xo {
             // const methods
 
             // non-const methods
-            /** move instance using collector **/
-            static Opaque shallow_move(DVsmEvalArgsFrame & self, obj<ACollector> gc) noexcept;
+            /** move instance using object visitor.
+Arguably abusing the word 'visitor' here **/
+            static Opaque gco_shallow_move(DVsmEvalArgsFrame & self, obj<AGCObjectVisitor> gc) noexcept;
             /** Invoke fn.visit_child(iface,data) for each child GCObject pointer.
 Context: provides address of data pointer so it can be updated in place
 when @p fn invokes garbage collector reentry point **/
diff --git a/include/xo/interpreter2/env/IGCObject_DLocalEnv.hpp b/include/xo/interpreter2/env/IGCObject_DLocalEnv.hpp
index cb5bdc49..29484934 100644
--- a/include/xo/interpreter2/env/IGCObject_DLocalEnv.hpp
+++ b/include/xo/interpreter2/env/IGCObject_DLocalEnv.hpp
@@ -53,8 +53,9 @@ namespace xo {
             // const methods
 
             // non-const methods
-            /** move instance using collector **/
-            static Opaque shallow_move(DLocalEnv & self, obj<ACollector> gc) noexcept;
+            /** move instance using object visitor.
+Arguably abusing the word 'visitor' here **/
+            static Opaque gco_shallow_move(DLocalEnv & self, obj<AGCObjectVisitor> gc) noexcept;
             /** Invoke fn.visit_child(iface,data) for each child GCObject pointer.
 Context: provides address of data pointer so it can be updated in place
 when @p fn invokes garbage collector reentry point **/
diff --git a/include/xo/interpreter2/ifelse/IGCObject_DVsmIfElseContFrame.hpp b/include/xo/interpreter2/ifelse/IGCObject_DVsmIfElseContFrame.hpp
index 1fc589f7..6812b6a0 100644
--- a/include/xo/interpreter2/ifelse/IGCObject_DVsmIfElseContFrame.hpp
+++ b/include/xo/interpreter2/ifelse/IGCObject_DVsmIfElseContFrame.hpp
@@ -53,8 +53,9 @@ namespace xo {
             // const methods
 
             // non-const methods
-            /** move instance using collector **/
-            static Opaque shallow_move(DVsmIfElseContFrame & self, obj<ACollector> gc) noexcept;
+            /** move instance using object visitor.
+Arguably abusing the word 'visitor' here **/
+            static Opaque gco_shallow_move(DVsmIfElseContFrame & self, obj<AGCObjectVisitor> gc) noexcept;
             /** Invoke fn.visit_child(iface,data) for each child GCObject pointer.
 Context: provides address of data pointer so it can be updated in place
 when @p fn invokes garbage collector reentry point **/
diff --git a/include/xo/interpreter2/sequence/IGCObject_DVsmSeqContFrame.hpp b/include/xo/interpreter2/sequence/IGCObject_DVsmSeqContFrame.hpp
index c8e20628..9b299d82 100644
--- a/include/xo/interpreter2/sequence/IGCObject_DVsmSeqContFrame.hpp
+++ b/include/xo/interpreter2/sequence/IGCObject_DVsmSeqContFrame.hpp
@@ -53,8 +53,9 @@ namespace xo {
             // const methods
 
             // non-const methods
-            /** move instance using collector **/
-            static Opaque shallow_move(DVsmSeqContFrame & self, obj<ACollector> gc) noexcept;
+            /** move instance using object visitor.
+Arguably abusing the word 'visitor' here **/
+            static Opaque gco_shallow_move(DVsmSeqContFrame & self, obj<AGCObjectVisitor> gc) noexcept;
             /** Invoke fn.visit_child(iface,data) for each child GCObject pointer.
 Context: provides address of data pointer so it can be updated in place
 when @p fn invokes garbage collector reentry point **/
diff --git a/include/xo/interpreter2/vsm/DVirtualSchematikaMachine.hpp b/include/xo/interpreter2/vsm/DVirtualSchematikaMachine.hpp
index 28343528..1b386aaa 100644
--- a/include/xo/interpreter2/vsm/DVirtualSchematikaMachine.hpp
+++ b/include/xo/interpreter2/vsm/DVirtualSchematikaMachine.hpp
@@ -71,7 +71,7 @@ namespace xo {
         public:
             // will be DArenaVector<obj<StackFrame>> probably
             using Stack = void *;
-            using ACollector = xo::mm::ACollector;
+            //using ACollector = xo::mm::ACollector;
             using AGCObject = xo::mm::AGCObject;
             using AGCObjectVisitor = xo::mm::AGCObjectVisitor;
             using AAllocator = xo::mm::AAllocator;
@@ -154,7 +154,7 @@ namespace xo {
             /** shallow copy during gc cycle.  Not implemented!  Only intending to support
              *  VSM as virtual root
              **/
-            DVirtualSchematikaMachine * shallow_move(obj<ACollector> gc) noexcept;
+            DVirtualSchematikaMachine * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
 
             /** forward gc-aware child pointers
              **/
diff --git a/include/xo/interpreter2/vsm/IGCObject_DVirtualSchematikaMachine.hpp b/include/xo/interpreter2/vsm/IGCObject_DVirtualSchematikaMachine.hpp
index 55497fad..c7d1d1f7 100644
--- a/include/xo/interpreter2/vsm/IGCObject_DVirtualSchematikaMachine.hpp
+++ b/include/xo/interpreter2/vsm/IGCObject_DVirtualSchematikaMachine.hpp
@@ -53,8 +53,9 @@ namespace xo {
             // const methods
 
             // non-const methods
-            /** move instance using collector **/
-            static Opaque shallow_move(DVirtualSchematikaMachine & self, obj<ACollector> gc) noexcept;
+            /** move instance using object visitor.
+Arguably abusing the word 'visitor' here **/
+            static Opaque gco_shallow_move(DVirtualSchematikaMachine & self, obj<AGCObjectVisitor> gc) noexcept;
             /** Invoke fn.visit_child(iface,data) for each child GCObject pointer.
 Context: provides address of data pointer so it can be updated in place
 when @p fn invokes garbage collector reentry point **/
diff --git a/src/interpreter2/DClosure.cpp b/src/interpreter2/DClosure.cpp
index ea8bcb15..684eb5d0 100644
--- a/src/interpreter2/DClosure.cpp
+++ b/src/interpreter2/DClosure.cpp
@@ -65,7 +65,7 @@ namespace xo {
         }
 
         DClosure *
-        DClosure::shallow_move(obj<ACollector> gc) noexcept {
+        DClosure::gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept {
             return gc.std_move_for(this);
         }
 
diff --git a/src/interpreter2/DLocalEnv.cpp b/src/interpreter2/DLocalEnv.cpp
index 3da6fd9b..e0fe0e79 100644
--- a/src/interpreter2/DLocalEnv.cpp
+++ b/src/interpreter2/DLocalEnv.cpp
@@ -92,7 +92,7 @@ namespace xo {
         }
 
         DLocalEnv *
-        DLocalEnv::shallow_move(obj<ACollector> gc) noexcept {
+        DLocalEnv::gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept {
             return gc.std_move_for(this);
         }
 
diff --git a/src/interpreter2/DVirtualSchematikaMachine.cpp b/src/interpreter2/DVirtualSchematikaMachine.cpp
index 8f9d3967..01c56698 100644
--- a/src/interpreter2/DVirtualSchematikaMachine.cpp
+++ b/src/interpreter2/DVirtualSchematikaMachine.cpp
@@ -954,8 +954,11 @@ namespace xo {
         }
 
         DVirtualSchematikaMachine *
-        DVirtualSchematikaMachine::shallow_move(obj<ACollector> gc) noexcept
+        DVirtualSchematikaMachine::gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept
         {
+            // need move-ctor on abox<..>
+            //return gc.std_move_for(this);
+
             (void)gc;
 
             /** TODO: should be able to use gc.std_move_for(this) now
diff --git a/src/interpreter2/DVsmApplyClosureFrame.cpp b/src/interpreter2/DVsmApplyClosureFrame.cpp
index c17414b8..dbb1601c 100644
--- a/src/interpreter2/DVsmApplyClosureFrame.cpp
+++ b/src/interpreter2/DVsmApplyClosureFrame.cpp
@@ -33,7 +33,7 @@ namespace xo {
         }
 
         DVsmApplyClosureFrame *
-        DVsmApplyClosureFrame::shallow_move(obj<ACollector> gc) noexcept
+        DVsmApplyClosureFrame::gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept
         {
             return gc.std_move_for(this);
         }
diff --git a/src/interpreter2/DVsmApplyFrame.cpp b/src/interpreter2/DVsmApplyFrame.cpp
index 1a9a946d..19db4bdf 100644
--- a/src/interpreter2/DVsmApplyFrame.cpp
+++ b/src/interpreter2/DVsmApplyFrame.cpp
@@ -41,7 +41,7 @@ namespace xo {
         }
 
         DVsmApplyFrame *
-        DVsmApplyFrame::shallow_move(obj<ACollector> gc) noexcept
+        DVsmApplyFrame::gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept
         {
             return gc.std_move_for(this);
         }
diff --git a/src/interpreter2/DVsmDefContFrame.cpp b/src/interpreter2/DVsmDefContFrame.cpp
index 0014f1a3..97b12ab0 100644
--- a/src/interpreter2/DVsmDefContFrame.cpp
+++ b/src/interpreter2/DVsmDefContFrame.cpp
@@ -32,7 +32,7 @@ namespace xo {
         // gcobject facet
 
         DVsmDefContFrame *
-        DVsmDefContFrame::shallow_move(obj<ACollector> gc) noexcept
+        DVsmDefContFrame::gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept
         {
             return gc.std_move_for<DVsmDefContFrame>(this);
         }
diff --git a/src/interpreter2/DVsmEvalArgsFrame.cpp b/src/interpreter2/DVsmEvalArgsFrame.cpp
index b796bb78..42d44de5 100644
--- a/src/interpreter2/DVsmEvalArgsFrame.cpp
+++ b/src/interpreter2/DVsmEvalArgsFrame.cpp
@@ -42,7 +42,7 @@ namespace xo {
         }
 
         DVsmEvalArgsFrame *
-        DVsmEvalArgsFrame::shallow_move(obj<ACollector> gc) noexcept
+        DVsmEvalArgsFrame::gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept
         {
             return gc.std_move_for(this);
         }
diff --git a/src/interpreter2/DVsmIfElseContFrame.cpp b/src/interpreter2/DVsmIfElseContFrame.cpp
index d0edd976..a82206bc 100644
--- a/src/interpreter2/DVsmIfElseContFrame.cpp
+++ b/src/interpreter2/DVsmIfElseContFrame.cpp
@@ -30,7 +30,7 @@ namespace xo {
         // gcobject facet
 
         DVsmIfElseContFrame *
-        DVsmIfElseContFrame::shallow_move(obj<ACollector> gc) noexcept
+        DVsmIfElseContFrame::gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept
         {
             return gc.std_move_for<DVsmIfElseContFrame>(this);
         }
diff --git a/src/interpreter2/DVsmSeqContFrame.cpp b/src/interpreter2/DVsmSeqContFrame.cpp
index f9ef2f0b..cb031b18 100644
--- a/src/interpreter2/DVsmSeqContFrame.cpp
+++ b/src/interpreter2/DVsmSeqContFrame.cpp
@@ -33,9 +33,9 @@ namespace xo {
         // gcobject facet
 
         DVsmSeqContFrame *
-        DVsmSeqContFrame::shallow_move(obj<ACollector> gc) noexcept
+        DVsmSeqContFrame::gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept
         {
-            return gc.std_move_for<DVsmSeqContFrame>(this);
+            return gc.std_move_for(this);
         }
 
         void
diff --git a/src/interpreter2/IGCObject_DClosure.cpp b/src/interpreter2/IGCObject_DClosure.cpp
index 889567bc..be0c9903 100644
--- a/src/interpreter2/IGCObject_DClosure.cpp
+++ b/src/interpreter2/IGCObject_DClosure.cpp
@@ -16,9 +16,9 @@
 namespace xo {
     namespace scm {
         auto
-        IGCObject_DClosure::shallow_move(DClosure & self, obj<ACollector> gc) noexcept -> Opaque
+        IGCObject_DClosure::gco_shallow_move(DClosure & self, obj<AGCObjectVisitor> gc) noexcept -> Opaque
         {
-            return self.shallow_move(gc);
+            return self.gco_shallow_move(gc);
         }
         auto
         IGCObject_DClosure::visit_gco_children(DClosure & self, obj<AGCObjectVisitor> fn) noexcept -> void
diff --git a/src/interpreter2/IGCObject_DVsmApplyClosureFrame.cpp b/src/interpreter2/IGCObject_DVsmApplyClosureFrame.cpp
index be67179b..5fcb724a 100644
--- a/src/interpreter2/IGCObject_DVsmApplyClosureFrame.cpp
+++ b/src/interpreter2/IGCObject_DVsmApplyClosureFrame.cpp
@@ -16,9 +16,9 @@
 namespace xo {
     namespace scm {
         auto
-        IGCObject_DVsmApplyClosureFrame::shallow_move(DVsmApplyClosureFrame & self, obj<ACollector> gc) noexcept -> Opaque
+        IGCObject_DVsmApplyClosureFrame::gco_shallow_move(DVsmApplyClosureFrame & self, obj<AGCObjectVisitor> gc) noexcept -> Opaque
         {
-            return self.shallow_move(gc);
+            return self.gco_shallow_move(gc);
         }
         auto
         IGCObject_DVsmApplyClosureFrame::visit_gco_children(DVsmApplyClosureFrame & self, obj<AGCObjectVisitor> fn) noexcept -> void
diff --git a/src/interpreter2/IGCObject_DVsmApplyFrame.cpp b/src/interpreter2/IGCObject_DVsmApplyFrame.cpp
index d3078821..4e8adef7 100644
--- a/src/interpreter2/IGCObject_DVsmApplyFrame.cpp
+++ b/src/interpreter2/IGCObject_DVsmApplyFrame.cpp
@@ -16,9 +16,9 @@
 namespace xo {
     namespace scm {
         auto
-        IGCObject_DVsmApplyFrame::shallow_move(DVsmApplyFrame & self, obj<ACollector> gc) noexcept -> Opaque
+        IGCObject_DVsmApplyFrame::gco_shallow_move(DVsmApplyFrame & self, obj<AGCObjectVisitor> gc) noexcept -> Opaque
         {
-            return self.shallow_move(gc);
+            return self.gco_shallow_move(gc);
         }
         auto
         IGCObject_DVsmApplyFrame::visit_gco_children(DVsmApplyFrame & self, obj<AGCObjectVisitor> fn) noexcept -> void
diff --git a/src/interpreter2/IGCObject_DVsmDefContFrame.cpp b/src/interpreter2/IGCObject_DVsmDefContFrame.cpp
index b3de6d94..60cb90d0 100644
--- a/src/interpreter2/IGCObject_DVsmDefContFrame.cpp
+++ b/src/interpreter2/IGCObject_DVsmDefContFrame.cpp
@@ -16,9 +16,9 @@
 namespace xo {
     namespace scm {
         auto
-        IGCObject_DVsmDefContFrame::shallow_move(DVsmDefContFrame & self, obj<ACollector> gc) noexcept -> Opaque
+        IGCObject_DVsmDefContFrame::gco_shallow_move(DVsmDefContFrame & self, obj<AGCObjectVisitor> gc) noexcept -> Opaque
         {
-            return self.shallow_move(gc);
+            return self.gco_shallow_move(gc);
         }
         auto
         IGCObject_DVsmDefContFrame::visit_gco_children(DVsmDefContFrame & self, obj<AGCObjectVisitor> fn) noexcept -> void
diff --git a/src/interpreter2/IGCObject_DVsmEvalArgsFrame.cpp b/src/interpreter2/IGCObject_DVsmEvalArgsFrame.cpp
index edf1768b..c9697c90 100644
--- a/src/interpreter2/IGCObject_DVsmEvalArgsFrame.cpp
+++ b/src/interpreter2/IGCObject_DVsmEvalArgsFrame.cpp
@@ -16,9 +16,9 @@
 namespace xo {
     namespace scm {
         auto
-        IGCObject_DVsmEvalArgsFrame::shallow_move(DVsmEvalArgsFrame & self, obj<ACollector> gc) noexcept -> Opaque
+        IGCObject_DVsmEvalArgsFrame::gco_shallow_move(DVsmEvalArgsFrame & self, obj<AGCObjectVisitor> gc) noexcept -> Opaque
         {
-            return self.shallow_move(gc);
+            return self.gco_shallow_move(gc);
         }
         auto
         IGCObject_DVsmEvalArgsFrame::visit_gco_children(DVsmEvalArgsFrame & self, obj<AGCObjectVisitor> fn) noexcept -> void
diff --git a/src/interpreter2/IGCObject_DVsmIfElseContFrame.cpp b/src/interpreter2/IGCObject_DVsmIfElseContFrame.cpp
index 6f73f5a8..d8fa856d 100644
--- a/src/interpreter2/IGCObject_DVsmIfElseContFrame.cpp
+++ b/src/interpreter2/IGCObject_DVsmIfElseContFrame.cpp
@@ -16,9 +16,9 @@
 namespace xo {
     namespace scm {
         auto
-        IGCObject_DVsmIfElseContFrame::shallow_move(DVsmIfElseContFrame & self, obj<ACollector> gc) noexcept -> Opaque
+        IGCObject_DVsmIfElseContFrame::gco_shallow_move(DVsmIfElseContFrame & self, obj<AGCObjectVisitor> gc) noexcept -> Opaque
         {
-            return self.shallow_move(gc);
+            return self.gco_shallow_move(gc);
         }
         auto
         IGCObject_DVsmIfElseContFrame::visit_gco_children(DVsmIfElseContFrame & self, obj<AGCObjectVisitor> fn) noexcept -> void
diff --git a/src/interpreter2/IGCObject_DVsmSeqContFrame.cpp b/src/interpreter2/IGCObject_DVsmSeqContFrame.cpp
index 437ac776..aa004bce 100644
--- a/src/interpreter2/IGCObject_DVsmSeqContFrame.cpp
+++ b/src/interpreter2/IGCObject_DVsmSeqContFrame.cpp
@@ -16,9 +16,9 @@
 namespace xo {
     namespace scm {
         auto
-        IGCObject_DVsmSeqContFrame::shallow_move(DVsmSeqContFrame & self, obj<ACollector> gc) noexcept -> Opaque
+        IGCObject_DVsmSeqContFrame::gco_shallow_move(DVsmSeqContFrame & self, obj<AGCObjectVisitor> gc) noexcept -> Opaque
         {
-            return self.shallow_move(gc);
+            return self.gco_shallow_move(gc);
         }
         auto
         IGCObject_DVsmSeqContFrame::visit_gco_children(DVsmSeqContFrame & self, obj<AGCObjectVisitor> fn) noexcept -> void
diff --git a/src/interpreter2/facet/IGCObject_DLocalEnv.cpp b/src/interpreter2/facet/IGCObject_DLocalEnv.cpp
index 2b8e4e93..eb107a81 100644
--- a/src/interpreter2/facet/IGCObject_DLocalEnv.cpp
+++ b/src/interpreter2/facet/IGCObject_DLocalEnv.cpp
@@ -16,9 +16,9 @@
 namespace xo {
     namespace scm {
         auto
-        IGCObject_DLocalEnv::shallow_move(DLocalEnv & self, obj<ACollector> gc) noexcept -> Opaque
+        IGCObject_DLocalEnv::gco_shallow_move(DLocalEnv & self, obj<AGCObjectVisitor> gc) noexcept -> Opaque
         {
-            return self.shallow_move(gc);
+            return self.gco_shallow_move(gc);
         }
         auto
         IGCObject_DLocalEnv::visit_gco_children(DLocalEnv & self, obj<AGCObjectVisitor> fn) noexcept -> void
diff --git a/src/interpreter2/facet/IGCObject_DVirtualSchematikaMachine.cpp b/src/interpreter2/facet/IGCObject_DVirtualSchematikaMachine.cpp
index 7fa74f97..c894ec35 100644
--- a/src/interpreter2/facet/IGCObject_DVirtualSchematikaMachine.cpp
+++ b/src/interpreter2/facet/IGCObject_DVirtualSchematikaMachine.cpp
@@ -16,9 +16,9 @@
 namespace xo {
     namespace scm {
         auto
-        IGCObject_DVirtualSchematikaMachine::shallow_move(DVirtualSchematikaMachine & self, obj<ACollector> gc) noexcept -> Opaque
+        IGCObject_DVirtualSchematikaMachine::gco_shallow_move(DVirtualSchematikaMachine & self, obj<AGCObjectVisitor> gc) noexcept -> Opaque
         {
-            return self.shallow_move(gc);
+            return self.gco_shallow_move(gc);
         }
         auto
         IGCObject_DVirtualSchematikaMachine::visit_gco_children(DVirtualSchematikaMachine & self, obj<AGCObjectVisitor> fn) noexcept -> void