diff --git a/include/xo/reader/exprstate.hpp b/include/xo/reader/exprstate.hpp
index fa0b466f..ced48160 100644
--- a/include/xo/reader/exprstate.hpp
+++ b/include/xo/reader/exprstate.hpp
@@ -56,34 +56,23 @@ namespace xo {
 
         public:
             exprstate() = default;
-            exprstate(exprstatetype exs_type,
-                      rp<Expression> candidate_expr)
-                : exs_type_{exs_type},
-                  gen_expr_{std::move(candidate_expr)} {}
+            exprstate(exprstatetype exs_type)
+                : exs_type_{exs_type}
+                {}
             virtual ~exprstate() = default;
 
             static std::unique_ptr<exprstate> expect_toplevel_expression_sequence() {
-                return std::make_unique<exprstate>(exprstate(exprstatetype::expect_toplevel_expression_sequence, nullptr));
+                return std::make_unique<exprstate>(exprstate(exprstatetype::expect_toplevel_expression_sequence));
             }
             static std::unique_ptr<exprstate> expect_rhs_expression() {
-                return std::make_unique<exprstate>(exprstate(exprstatetype::expect_rhs_expression, nullptr));
+                return std::make_unique<exprstate>(exprstate(exprstatetype::expect_rhs_expression));
             }
             static std::unique_ptr<exprstate> expect_symbol() {
-                return std::make_unique<exprstate>(exprstate(exprstatetype::expect_symbol, nullptr));
+                return std::make_unique<exprstate>(exprstate(exprstatetype::expect_symbol));
             }
             static std::unique_ptr<exprstate> expect_type() {
-                return std::make_unique<exprstate>(exprstate(exprstatetype::expect_type, nullptr));
+                return std::make_unique<exprstate>(exprstate(exprstatetype::expect_type));
             }
-#ifdef RELOCATED
-            static std::unique_ptr<exprstate> make_expr_progress(rp<Expression> expr) {
-                return std::make_unique<exprstate>(exprstate(exprstatetype::expr_progress, expr));
-            }
-#endif
-#ifdef RELOCATED
-            static std::unique_ptr<exprstate> lparen_0() {
-                return std::make_unique<exprstate>(exprstate(exprstatetype::lparen_0, nullptr));
-            }
-#endif
 
             exprstatetype exs_type() const { return exs_type_; }
 
@@ -144,10 +133,8 @@ namespace xo {
                                 rp<Expression> * p_emit_expr);
 
         protected:
+            /** explicit subtype: identifies derived class **/
             exprstatetype exs_type_;
-
-            /** generic expression **/
-            rp<Expression> gen_expr_;
         }; /*exprstate*/
 
         inline std::ostream &
diff --git a/include/xo/reader/paren_xs.hpp b/include/xo/reader/paren_xs.hpp
index a6a8eb3e..91d4a633 100644
--- a/include/xo/reader/paren_xs.hpp
+++ b/include/xo/reader/paren_xs.hpp
@@ -78,6 +78,8 @@ namespace xo {
              *   lparen_0
              **/
             parenexprstatetype parenxs_type_;
+            /** populate expression (representing parenthesized value) here **/
+            rp<Expression> gen_expr_;
         };
     } /*namespace scm*/
 } /*namespace xo*/
diff --git a/include/xo/reader/progress_xs.hpp b/include/xo/reader/progress_xs.hpp
index 5b2ce28f..62fba624 100644
--- a/include/xo/reader/progress_xs.hpp
+++ b/include/xo/reader/progress_xs.hpp
@@ -58,10 +58,8 @@ namespace xo {
             virtual void print(std::ostream & os) const override;
 
         private:
-#ifdef NOT_YET
             /** populate an expression here **/
             rp<Expression> gen_expr_;
-#endif
         };
     } /*namespace scm*/
 } /*namespace xo*/
diff --git a/src/reader/define_xs.cpp b/src/reader/define_xs.cpp
index d1f93984..5ecb82f5 100644
--- a/src/reader/define_xs.cpp
+++ b/src/reader/define_xs.cpp
@@ -10,8 +10,7 @@ namespace xo {
         }
 
         define_xs::define_xs(rp<DefineExprAccess> def_expr)
-            : exprstate(exprstatetype::defexpr,
-                        nullptr /*gen_expr*/),
+            : exprstate(exprstatetype::defexpr),
               defxs_type_{defexprstatetype::def_0},
               def_expr_{std::move(def_expr)}
         {}
diff --git a/src/reader/progress_xs.cpp b/src/reader/progress_xs.cpp
index 6e1d743a..2070e909 100644
--- a/src/reader/progress_xs.cpp
+++ b/src/reader/progress_xs.cpp
@@ -10,8 +10,8 @@ namespace xo {
         }
 
         progress_xs::progress_xs(rp<Expression> valex)
-            : exprstate(exprstatetype::expr_progress,
-                        std::move(valex))
+            : exprstate(exprstatetype::expr_progress),
+              gen_expr_{std::move(valex)}
         {}
 
         bool