diff --git a/CMakeLists.txt b/CMakeLists.txt
index f286f2ad..52e9d380 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -44,6 +44,8 @@ xo_add_genfacet(
     OUTPUT_CPP_DIR src/expression2
     )
 
+# ----------------------------------------------------------------
+
 # note: manual target; generated code committed to git
 xo_add_genfacetimpl(
     TARGET xo-expression2-facetimpl-expression-constant
@@ -56,6 +58,18 @@ xo_add_genfacetimpl(
     OUTPUT_CPP_DIR src/expression2
 )
 
+# note: manual target; generated code committed to git
+xo_add_genfacetimpl(
+    TARGET xo-expression2-facetimpl-printable-constant
+    FACET_PKG xo_printable2
+    FACET Printable
+    REPR Constant
+    INPUT idl/IPrintable_DConstant.json5
+    OUTPUT_HPP_DIR include/xo/expression2
+    OUTPUT_IMPL_SUBDIR detail
+    OUTPUT_CPP_DIR src/expression2
+)
+
 # ----------------------------------------------------------------
 
 # note: manual target; generated code committed to git
diff --git a/idl/IPrintable_DConstant.json5 b/idl/IPrintable_DConstant.json5
new file mode 100644
index 00000000..1d955d79
--- /dev/null
+++ b/idl/IPrintable_DConstant.json5
@@ -0,0 +1,13 @@
+{
+    mode: "implementation",
+    includes: [ "<xo/printable2/Printable.hpp>",
+                "<xo/printable2/detail/IPrintable_Xfer.hpp>" ],
+    local_types: [ ],
+    namespace1: "xo",
+    namespace2: "scm",
+    facet_idl: "idl/Printable.json5",
+    brief: "provide APrintable interface for DConstant",
+    using_doxygen: true,
+    repr: "DConstant",
+    doc: [ "implement APrintable for DConstant" ],
+}
diff --git a/include/xo/expression2/DConstant.hpp b/include/xo/expression2/DConstant.hpp
index a73ea2df..81561e68 100644
--- a/include/xo/expression2/DConstant.hpp
+++ b/include/xo/expression2/DConstant.hpp
@@ -22,6 +22,7 @@ namespace xo {
             using AAllocator = xo::mm::AAllocator;
             using AGCObject = xo::mm::AGCObject;
             using typeseq = xo::reflect::typeseq;
+            using ppindentinfo = xo::print::ppindentinfo;
 
         public:
             explicit DConstant(obj<AGCObject> value) noexcept;
@@ -45,6 +46,8 @@ namespace xo {
 
             void assign_valuetype(TypeDescr td) noexcept { typeref_.resolve(td); }
 
+            bool pretty(const ppindentinfo & ppii) const;
+
         private:
             static TypeDescr _lookup_td(typeseq tseq);
 
diff --git a/include/xo/expression2/detail/IPrintable_DConstant.hpp b/include/xo/expression2/detail/IPrintable_DConstant.hpp
new file mode 100644
index 00000000..a1e31382
--- /dev/null
+++ b/include/xo/expression2/detail/IPrintable_DConstant.hpp
@@ -0,0 +1,62 @@
+/** @file IPrintable_DConstant.hpp
+ *
+ *  Generated automagically from ingredients:
+ *  1. code generator:
+ *       [/home/roland/proj/xo-umbrella2-claude1/xo-facet/codegen/genfacet]
+ *     arguments:
+ *       --input [idl/IPrintable_DConstant.json5]
+ *  2. jinja2 template for abstract facet .hpp file:
+ *       [iface_facet_repr.hpp.j2]
+ *  3. idl for facet methods
+ *       [idl/IPrintable_DConstant.json5]
+ **/
+
+#pragma once
+
+#include "Printable.hpp"
+#include <xo/printable2/Printable.hpp>
+#include <xo/printable2/detail/IPrintable_Xfer.hpp>
+#include "DConstant.hpp"
+
+namespace xo { namespace scm { class IPrintable_DConstant; } }
+
+namespace xo {
+    namespace facet {
+        template <>
+        struct FacetImplementation<xo::print::APrintable,
+                                   xo::scm::DConstant>
+        {
+            using ImplType = xo::print::IPrintable_Xfer
+              <xo::scm::DConstant,
+               xo::scm::IPrintable_DConstant>;
+        };
+    }
+}
+
+namespace xo {
+    namespace scm {
+        /** @class IPrintable_DConstant
+         **/
+        class IPrintable_DConstant {
+        public:
+            /** @defgroup scm-printable-dconstant-type-traits **/
+            ///@{
+            using ppindentinfo = xo::print::APrintable::ppindentinfo;
+            using Copaque = xo::print::APrintable::Copaque;
+            using Opaque = xo::print::APrintable::Opaque;
+            ///@}
+            /** @defgroup scm-printable-dconstant-methods **/
+            ///@{
+            // const methods
+            /** Pretty-printing support for this object.
+See [xo-indentlog/xo/indentlog/pretty.hpp] **/
+            static bool pretty(const DConstant & self, const ppindentinfo & ppii);
+
+            // non-const methods
+            ///@}
+        };
+
+    } /*namespace scm*/
+} /*namespace xo*/
+
+/* end */
\ No newline at end of file
diff --git a/src/expression2/CMakeLists.txt b/src/expression2/CMakeLists.txt
index f2dfe7e7..17c34275 100644
--- a/src/expression2/CMakeLists.txt
+++ b/src/expression2/CMakeLists.txt
@@ -11,7 +11,9 @@ set(SELF_SRCS
     TypeRef.cpp
 
     IExpression_Any.cpp
+
     IExpression_DConstant.cpp
+    IPrintable_DConstant.cpp
 
     IExpression_DVariable.cpp
     IPrintable_DVariable.cpp
diff --git a/src/expression2/DConstant.cpp b/src/expression2/DConstant.cpp
index 5bf98bfc..a0b255a6 100644
--- a/src/expression2/DConstant.cpp
+++ b/src/expression2/DConstant.cpp
@@ -7,12 +7,16 @@
 #include "TypeDescr.hpp"
 #include <xo/object2/DFloat.hpp>
 #include <xo/object2/DInteger.hpp>
+#include <xo/facet/FacetRegistry.hpp>
 #include <xo/reflect/Reflect.hpp>
+#include <xo/printable2/Printable.hpp>
 #include <xo/reflectutil/typeseq.hpp>
 
 namespace xo {
     using xo::scm::DFloat;
     using xo::scm::DInteger;
+    using xo::print::APrintable;
+    using xo::facet::FacetRegistry;
     using xo::reflect::Reflect;
     using xo::reflect::TypeDescr;
     using xo::reflect::typeseq;
@@ -57,6 +61,20 @@ namespace xo {
 
             return nullptr;
         }
+
+        bool
+        DConstant::pretty(const ppindentinfo & ppii) const
+        {
+            obj<APrintable> value
+                = FacetRegistry::instance().variant<APrintable,AGCObject>(value_);
+
+            return ppii.pps()->pretty_struct
+                       (ppii,
+                        "DConstant",
+                        refrtag("value_.tseq", value_._typeseq()),
+                        refrtag("value.tseq", value._typeseq()),
+                        refrtag("value", value));
+        }
     } /*namespace scm*/
 } /*namespace xo*/
 
diff --git a/src/expression2/DDefineExpr.cpp b/src/expression2/DDefineExpr.cpp
index e193c4d4..47465c0e 100644
--- a/src/expression2/DDefineExpr.cpp
+++ b/src/expression2/DDefineExpr.cpp
@@ -79,11 +79,21 @@ namespace xo {
             auto rhs = FacetRegistry::instance().try_variant<APrintable,
                                                              AExpression>(rhs_);
 
-            return ppii.pps()->pretty_struct
-                       (ppii,
-                        "DDefineExpr",
-                        refrtag("lhs", lhs),
-                        refrtag("rhs", cond(rhs_, rhs, "nullptr")));
+            // note: xo::print::cond() doesn't resolve the way we want here
+
+            if (rhs) {
+                return ppii.pps()->pretty_struct
+                           (ppii,
+                            "DDefineExpr",
+                            refrtag("lhs", lhs),
+                            refrtag("rhs", rhs));
+            } else {
+                return ppii.pps()->pretty_struct
+                           (ppii,
+                            "DDefineExpr",
+                            refrtag("lhs", lhs));
+
+            }
         }
 
     } /*namespace scm*/
diff --git a/src/expression2/IPrintable_DConstant.cpp b/src/expression2/IPrintable_DConstant.cpp
new file mode 100644
index 00000000..1bacfb9d
--- /dev/null
+++ b/src/expression2/IPrintable_DConstant.cpp
@@ -0,0 +1,28 @@
+/** @file IPrintable_DConstant.cpp
+ *
+ *  Generated automagically from ingredients:
+ *  1. code generator:
+ *       [/home/roland/proj/xo-umbrella2-claude1/xo-facet/codegen/genfacet]
+ *     arguments:
+ *       --input [idl/IPrintable_DConstant.json5]
+ *  2. jinja2 template for abstract facet .hpp file:
+ *       [iface_facet_any.hpp.j2]
+ *  3. idl for facet methods
+ *       [idl/IPrintable_DConstant.json5]
+**/
+
+#include "detail/IPrintable_DConstant.hpp"
+
+namespace xo {
+    namespace scm {
+        auto
+        IPrintable_DConstant::pretty(const DConstant & self, const ppindentinfo & ppii) -> bool
+        {
+            return self.pretty(ppii);
+        }
+
+
+    } /*namespace scm*/
+} /*namespace xo*/
+
+/* end IPrintable_DConstant.cpp */
\ No newline at end of file
diff --git a/src/expression2/expression2_register_facets.cpp b/src/expression2/expression2_register_facets.cpp
index e6715769..1854f3eb 100644
--- a/src/expression2/expression2_register_facets.cpp
+++ b/src/expression2/expression2_register_facets.cpp
@@ -8,10 +8,15 @@
 #include <xo/expression2/detail/IGCObject_DUniqueString.hpp>
 #include <xo/expression2/detail/IPrintable_DUniqueString.hpp>
 
+#include <xo/expression2/detail/IExpression_DDefineExpr.hpp>
 #include <xo/expression2/detail/IPrintable_DDefineExpr.hpp>
 
+#include <xo/expression2/detail/IExpression_DVariable.hpp>
 #include <xo/expression2/detail/IPrintable_DVariable.hpp>
 
+#include <xo/expression2/detail/IExpression_DConstant.hpp>
+#include <xo/expression2/detail/IPrintable_DConstant.hpp>
+
 #include <xo/gc/detail/AGCObject.hpp>
 #include <xo/printable2/detail/APrintable.hpp>
 #include <xo/facet/FacetRegistry.hpp>
@@ -32,13 +37,24 @@ namespace xo {
             FacetRegistry::register_impl<AGCObject, DUniqueString>();
             FacetRegistry::register_impl<APrintable, DUniqueString>();
 
-            FacetRegistry::register_impl<APrintable, DDefineExpr>();
+            // Expression
+            // +- Constant
+            // +- Variable
+            // \- DefineExpr
 
+            FacetRegistry::register_impl<AExpression, DConstant>();
+            FacetRegistry::register_impl<APrintable, DConstant>();
+
+            FacetRegistry::register_impl<AExpression, DVariable>();
             FacetRegistry::register_impl<APrintable, DVariable>();
 
+            FacetRegistry::register_impl<AExpression, DDefineExpr>();
+            FacetRegistry::register_impl<APrintable, DDefineExpr>();
+
             log && log(xtag("DUniqueString.tseq", typeseq::id<DUniqueString>()));
             log && log(xtag("DDefineExpr.tseq", typeseq::id<DDefineExpr>()));
             log && log(xtag("DVariable.tseq", typeseq::id<DVariable>()));
+            log && log(xtag("DConstant.tseq", typeseq::id<DConstant>()));
 
             log && log(xtag("AExpression.tqseq", typeseq::id<AExpression>()));