diff --git a/cmake/xo_reader2Config.cmake.in b/cmake/xo_reader2Config.cmake.in
index 14dec967..6d032cb1 100644
--- a/cmake/xo_reader2Config.cmake.in
+++ b/cmake/xo_reader2Config.cmake.in
@@ -9,6 +9,7 @@ include(CMakeFindDependencyMacro)
 find_dependency(xo_numeric)
 find_dependency(xo_procedure2)
 find_dependency(xo_gc)
+find_dependency(xo_type)
 find_dependency(xo_tokenizer2)
 find_dependency(xo_expression2)
 find_dependency(subsys)
diff --git a/idl/SyntaxStateMachine.json5 b/idl/SyntaxStateMachine.json5
index 815fd18e..0238749c 100644
--- a/idl/SyntaxStateMachine.json5
+++ b/idl/SyntaxStateMachine.json5
@@ -7,6 +7,7 @@
     includes: [
         "\"ParserStateMachine.hpp\"",
         "\"syntaxstatetype.hpp\"",
+        "<xo/type/Type.hpp>",
         "<xo/tokenizer2/Token.hpp>",
         "<xo/reflect/TypeDescr.hpp>",
     ],
@@ -76,6 +77,15 @@
                 {type: "ParserStateMachine *", name: "p_psm"},
             ],
         },
+        {
+            name: "on_parsed_type",
+            doc: ["update state machine for type emitted by nested ssm"],
+            return_type: "void",
+            args: [
+                {type: "obj<AType>", name: "type"},
+                {type: "ParserStateMachine *", name: "p_psm"},
+            ],
+        },
         {
             name: "on_parsed_formal",
             doc: ["operate state machine for formal emitted by nested ssm"],
diff --git a/include/xo/reader2/DSyntaxStateMachine.hpp b/include/xo/reader2/DSyntaxStateMachine.hpp
index adce34e1..10aeccfa 100644
--- a/include/xo/reader2/DSyntaxStateMachine.hpp
+++ b/include/xo/reader2/DSyntaxStateMachine.hpp
@@ -44,6 +44,17 @@ namespace xo {
                                                   self.get_expect_str());
                 }
 
+            /** Explicit error path **/
+            void illegal_type(obj<AType> type,
+                              ParserStateMachine * p_psm)
+                {
+                    Derived & self = static_cast<Derived &>(*this);
+
+                    p_psm->illegal_input_on_type(Derived::ssm_classname(),
+                                                 type,
+                                                 self.get_expect_str());
+                }
+
             /** Explicit error path **/
             void illegal_quoted_literal(obj<AGCObject> lit,
                                         ParserStateMachine * p_psm)
@@ -88,6 +99,14 @@ namespace xo {
                                                   self.get_expect_str());
             }
 
+            /** Default implementation for require SyntaxStateMachine facet method
+             **/
+            void on_parsed_type(obj<AType> type,
+                                ParserStateMachine * p_psm)
+                {
+                    this->illegal_type(type, p_psm);
+                }
+
             /** Default implementation for required SyntaxStateMachine facet method
              **/
             void on_parsed_formal(const DUniqueString * param_name,
diff --git a/include/xo/reader2/ParserStateMachine.hpp b/include/xo/reader2/ParserStateMachine.hpp
index a247688a..2553acbf 100644
--- a/include/xo/reader2/ParserStateMachine.hpp
+++ b/include/xo/reader2/ParserStateMachine.hpp
@@ -11,6 +11,7 @@
 #include <xo/expression2/DVariable.hpp>
 #include <xo/expression2/VarRef.hpp>
 #include <xo/tokenizer2/Token.hpp>
+#include <xo/type/Type.hpp>
 #include <xo/object2/DArray.hpp>
 #include <xo/stringtable2/StringTable.hpp>
 #include <xo/alloc2/Allocator.hpp>
@@ -234,6 +235,14 @@ namespace xo {
                                             TypeDescr td,
                                             std::string_view expect_str);
 
+            /** report illegal input arriving in syntax state machine (ssm) @p ssm_name
+             *  when receiving type definition @p ty.
+             *  @p expect_str sketches expected input in current ssm state
+             **/
+            void illegal_input_on_type(std::string_view ssm_name,
+                                       obj<AType> ty,
+                                       std::string_view expect_str);
+
             /** report illegal parsed formal (param_name, param_type) from nested ssm.
              *  Introducing as placeholder; not expected to be reachable in
              *  full parser
diff --git a/include/xo/reader2/ssm/ASyntaxStateMachine.hpp b/include/xo/reader2/ssm/ASyntaxStateMachine.hpp
index b7fa0a92..a010421d 100644
--- a/include/xo/reader2/ssm/ASyntaxStateMachine.hpp
+++ b/include/xo/reader2/ssm/ASyntaxStateMachine.hpp
@@ -16,6 +16,7 @@
 // includes (via {facet_includes})
 #include "ParserStateMachine.hpp"
 #include "syntaxstatetype.hpp"
+#include <xo/type/Type.hpp>
 #include <xo/tokenizer2/Token.hpp>
 #include <xo/reflect/TypeDescr.hpp>
 #include <xo/facet/obj.hpp>
@@ -67,6 +68,8 @@ public:
     virtual void on_parsed_symbol(Opaque data, std::string_view sym, ParserStateMachine * p_psm)  = 0;
     /** operate state machine for incoming type description @p td **/
     virtual void on_parsed_typedescr(Opaque data, TypeDescr td, ParserStateMachine * p_psm)  = 0;
+    /** update state machine for type emitted by nested ssm **/
+    virtual void on_parsed_type(Opaque data, obj<AType> type, ParserStateMachine * p_psm)  = 0;
     /** operate state machine for formal emitted by nested ssm **/
     virtual void on_parsed_formal(Opaque data, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm)  = 0;
     /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_Any.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_Any.hpp
index 81d00656..2f00d0a4 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_Any.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_Any.hpp
@@ -67,6 +67,7 @@ namespace scm {
         [[noreturn]] void on_token(Opaque, const Token &, ParserStateMachine *)  override;
         [[noreturn]] void on_parsed_symbol(Opaque, std::string_view, ParserStateMachine *)  override;
         [[noreturn]] void on_parsed_typedescr(Opaque, TypeDescr, ParserStateMachine *)  override;
+        [[noreturn]] void on_parsed_type(Opaque, obj<AType>, ParserStateMachine *)  override;
         [[noreturn]] void on_parsed_formal(Opaque, const DUniqueString *, TypeDescr, ParserStateMachine *)  override;
         [[noreturn]] void on_parsed_formal_with_token(Opaque, const DUniqueString *, TypeDescr, const Token &, ParserStateMachine *)  override;
         [[noreturn]] void on_parsed_formal_arglist(Opaque, DArray *, ParserStateMachine *)  override;
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_DApplySsm.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_DApplySsm.hpp
index 75863bfc..0b0f6972 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_DApplySsm.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_DApplySsm.hpp
@@ -61,6 +61,8 @@ namespace xo {
             static void on_parsed_symbol(DApplySsm & self, std::string_view sym, ParserStateMachine * p_psm);
             /** operate state machine for incoming type description @p td **/
             static void on_parsed_typedescr(DApplySsm & self, TypeDescr td, ParserStateMachine * p_psm);
+            /** update state machine for type emitted by nested ssm **/
+            static void on_parsed_type(DApplySsm & self, obj<AType> type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
             static void on_parsed_formal(DApplySsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_DDefineSsm.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_DDefineSsm.hpp
index 0191de54..d8b28de8 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_DDefineSsm.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_DDefineSsm.hpp
@@ -61,6 +61,8 @@ namespace xo {
             static void on_parsed_symbol(DDefineSsm & self, std::string_view sym, ParserStateMachine * p_psm);
             /** operate state machine for incoming type description @p td **/
             static void on_parsed_typedescr(DDefineSsm & self, TypeDescr td, ParserStateMachine * p_psm);
+            /** update state machine for type emitted by nested ssm **/
+            static void on_parsed_type(DDefineSsm & self, obj<AType> type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
             static void on_parsed_formal(DDefineSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectExprSsm.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectExprSsm.hpp
index a84ed1b1..1cde9c14 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectExprSsm.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectExprSsm.hpp
@@ -61,6 +61,8 @@ namespace xo {
             static void on_parsed_symbol(DExpectExprSsm & self, std::string_view sym, ParserStateMachine * p_psm);
             /** operate state machine for incoming type description @p td **/
             static void on_parsed_typedescr(DExpectExprSsm & self, TypeDescr td, ParserStateMachine * p_psm);
+            /** update state machine for type emitted by nested ssm **/
+            static void on_parsed_type(DExpectExprSsm & self, obj<AType> type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
             static void on_parsed_formal(DExpectExprSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectFormalArgSsm.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectFormalArgSsm.hpp
index 4e924170..2c6da502 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectFormalArgSsm.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectFormalArgSsm.hpp
@@ -61,6 +61,8 @@ namespace xo {
             static void on_parsed_symbol(DExpectFormalArgSsm & self, std::string_view sym, ParserStateMachine * p_psm);
             /** operate state machine for incoming type description @p td **/
             static void on_parsed_typedescr(DExpectFormalArgSsm & self, TypeDescr td, ParserStateMachine * p_psm);
+            /** update state machine for type emitted by nested ssm **/
+            static void on_parsed_type(DExpectFormalArgSsm & self, obj<AType> type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
             static void on_parsed_formal(DExpectFormalArgSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectFormalArglistSsm.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectFormalArglistSsm.hpp
index d1e388b2..78e7db56 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectFormalArglistSsm.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectFormalArglistSsm.hpp
@@ -61,6 +61,8 @@ namespace xo {
             static void on_parsed_symbol(DExpectFormalArglistSsm & self, std::string_view sym, ParserStateMachine * p_psm);
             /** operate state machine for incoming type description @p td **/
             static void on_parsed_typedescr(DExpectFormalArglistSsm & self, TypeDescr td, ParserStateMachine * p_psm);
+            /** update state machine for type emitted by nested ssm **/
+            static void on_parsed_type(DExpectFormalArglistSsm & self, obj<AType> type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
             static void on_parsed_formal(DExpectFormalArglistSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectQArraySsm.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectQArraySsm.hpp
index 78018537..c77c635d 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectQArraySsm.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectQArraySsm.hpp
@@ -61,6 +61,8 @@ namespace xo {
             static void on_parsed_symbol(DExpectQArraySsm & self, std::string_view sym, ParserStateMachine * p_psm);
             /** operate state machine for incoming type description @p td **/
             static void on_parsed_typedescr(DExpectQArraySsm & self, TypeDescr td, ParserStateMachine * p_psm);
+            /** update state machine for type emitted by nested ssm **/
+            static void on_parsed_type(DExpectQArraySsm & self, obj<AType> type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
             static void on_parsed_formal(DExpectQArraySsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectQListSsm.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectQListSsm.hpp
index 6cd1a38b..14ff3627 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectQListSsm.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectQListSsm.hpp
@@ -61,6 +61,8 @@ namespace xo {
             static void on_parsed_symbol(DExpectQListSsm & self, std::string_view sym, ParserStateMachine * p_psm);
             /** operate state machine for incoming type description @p td **/
             static void on_parsed_typedescr(DExpectQListSsm & self, TypeDescr td, ParserStateMachine * p_psm);
+            /** update state machine for type emitted by nested ssm **/
+            static void on_parsed_type(DExpectQListSsm & self, obj<AType> type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
             static void on_parsed_formal(DExpectQListSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectQLiteralSsm.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectQLiteralSsm.hpp
index 303d137e..b19181a8 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectQLiteralSsm.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectQLiteralSsm.hpp
@@ -61,6 +61,8 @@ namespace xo {
             static void on_parsed_symbol(DExpectQLiteralSsm & self, std::string_view sym, ParserStateMachine * p_psm);
             /** operate state machine for incoming type description @p td **/
             static void on_parsed_typedescr(DExpectQLiteralSsm & self, TypeDescr td, ParserStateMachine * p_psm);
+            /** update state machine for type emitted by nested ssm **/
+            static void on_parsed_type(DExpectQLiteralSsm & self, obj<AType> type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
             static void on_parsed_formal(DExpectQLiteralSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectSymbolSsm.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectSymbolSsm.hpp
index f39e2af3..431cba69 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectSymbolSsm.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectSymbolSsm.hpp
@@ -61,6 +61,8 @@ namespace xo {
             static void on_parsed_symbol(DExpectSymbolSsm & self, std::string_view sym, ParserStateMachine * p_psm);
             /** operate state machine for incoming type description @p td **/
             static void on_parsed_typedescr(DExpectSymbolSsm & self, TypeDescr td, ParserStateMachine * p_psm);
+            /** update state machine for type emitted by nested ssm **/
+            static void on_parsed_type(DExpectSymbolSsm & self, obj<AType> type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
             static void on_parsed_formal(DExpectSymbolSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectTypeSsm.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectTypeSsm.hpp
index ba997e28..f43f83c7 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectTypeSsm.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_DExpectTypeSsm.hpp
@@ -61,6 +61,8 @@ namespace xo {
             static void on_parsed_symbol(DExpectTypeSsm & self, std::string_view sym, ParserStateMachine * p_psm);
             /** operate state machine for incoming type description @p td **/
             static void on_parsed_typedescr(DExpectTypeSsm & self, TypeDescr td, ParserStateMachine * p_psm);
+            /** update state machine for type emitted by nested ssm **/
+            static void on_parsed_type(DExpectTypeSsm & self, obj<AType> type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
             static void on_parsed_formal(DExpectTypeSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_DIfElseSsm.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_DIfElseSsm.hpp
index b189bf87..6b9dd33f 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_DIfElseSsm.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_DIfElseSsm.hpp
@@ -61,6 +61,8 @@ namespace xo {
             static void on_parsed_symbol(DIfElseSsm & self, std::string_view sym, ParserStateMachine * p_psm);
             /** operate state machine for incoming type description @p td **/
             static void on_parsed_typedescr(DIfElseSsm & self, TypeDescr td, ParserStateMachine * p_psm);
+            /** update state machine for type emitted by nested ssm **/
+            static void on_parsed_type(DIfElseSsm & self, obj<AType> type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
             static void on_parsed_formal(DIfElseSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_DLambdaSsm.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_DLambdaSsm.hpp
index 9c97287f..8ba94c58 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_DLambdaSsm.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_DLambdaSsm.hpp
@@ -61,6 +61,8 @@ namespace xo {
             static void on_parsed_symbol(DLambdaSsm & self, std::string_view sym, ParserStateMachine * p_psm);
             /** operate state machine for incoming type description @p td **/
             static void on_parsed_typedescr(DLambdaSsm & self, TypeDescr td, ParserStateMachine * p_psm);
+            /** update state machine for type emitted by nested ssm **/
+            static void on_parsed_type(DLambdaSsm & self, obj<AType> type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
             static void on_parsed_formal(DLambdaSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_DParenSsm.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_DParenSsm.hpp
index 65cd1727..ef74a525 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_DParenSsm.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_DParenSsm.hpp
@@ -61,6 +61,8 @@ namespace xo {
             static void on_parsed_symbol(DParenSsm & self, std::string_view sym, ParserStateMachine * p_psm);
             /** operate state machine for incoming type description @p td **/
             static void on_parsed_typedescr(DParenSsm & self, TypeDescr td, ParserStateMachine * p_psm);
+            /** update state machine for type emitted by nested ssm **/
+            static void on_parsed_type(DParenSsm & self, obj<AType> type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
             static void on_parsed_formal(DParenSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_DProgressSsm.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_DProgressSsm.hpp
index 431892b9..c5e91891 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_DProgressSsm.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_DProgressSsm.hpp
@@ -61,6 +61,8 @@ namespace xo {
             static void on_parsed_symbol(DProgressSsm & self, std::string_view sym, ParserStateMachine * p_psm);
             /** operate state machine for incoming type description @p td **/
             static void on_parsed_typedescr(DProgressSsm & self, TypeDescr td, ParserStateMachine * p_psm);
+            /** update state machine for type emitted by nested ssm **/
+            static void on_parsed_type(DProgressSsm & self, obj<AType> type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
             static void on_parsed_formal(DProgressSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_DQuoteSsm.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_DQuoteSsm.hpp
index e5548af5..7f776ca0 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_DQuoteSsm.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_DQuoteSsm.hpp
@@ -61,6 +61,8 @@ namespace xo {
             static void on_parsed_symbol(DQuoteSsm & self, std::string_view sym, ParserStateMachine * p_psm);
             /** operate state machine for incoming type description @p td **/
             static void on_parsed_typedescr(DQuoteSsm & self, TypeDescr td, ParserStateMachine * p_psm);
+            /** update state machine for type emitted by nested ssm **/
+            static void on_parsed_type(DQuoteSsm & self, obj<AType> type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
             static void on_parsed_formal(DQuoteSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_DSequenceSsm.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_DSequenceSsm.hpp
index 448b296b..361922ef 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_DSequenceSsm.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_DSequenceSsm.hpp
@@ -61,6 +61,8 @@ namespace xo {
             static void on_parsed_symbol(DSequenceSsm & self, std::string_view sym, ParserStateMachine * p_psm);
             /** operate state machine for incoming type description @p td **/
             static void on_parsed_typedescr(DSequenceSsm & self, TypeDescr td, ParserStateMachine * p_psm);
+            /** update state machine for type emitted by nested ssm **/
+            static void on_parsed_type(DSequenceSsm & self, obj<AType> type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
             static void on_parsed_formal(DSequenceSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_DToplevelSeqSsm.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_DToplevelSeqSsm.hpp
index 9aa70c43..fbb45bef 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_DToplevelSeqSsm.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_DToplevelSeqSsm.hpp
@@ -61,6 +61,8 @@ namespace xo {
             static void on_parsed_symbol(DToplevelSeqSsm & self, std::string_view sym, ParserStateMachine * p_psm);
             /** operate state machine for incoming type description @p td **/
             static void on_parsed_typedescr(DToplevelSeqSsm & self, TypeDescr td, ParserStateMachine * p_psm);
+            /** update state machine for type emitted by nested ssm **/
+            static void on_parsed_type(DToplevelSeqSsm & self, obj<AType> type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
             static void on_parsed_formal(DToplevelSeqSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm);
             /** operate state machine for formal emitted by nested ssm **/
diff --git a/include/xo/reader2/ssm/ISyntaxStateMachine_Xfer.hpp b/include/xo/reader2/ssm/ISyntaxStateMachine_Xfer.hpp
index 4a77f0c4..67b187cf 100644
--- a/include/xo/reader2/ssm/ISyntaxStateMachine_Xfer.hpp
+++ b/include/xo/reader2/ssm/ISyntaxStateMachine_Xfer.hpp
@@ -15,6 +15,7 @@
 
 #include "ParserStateMachine.hpp"
 #include "syntaxstatetype.hpp"
+#include <xo/type/Type.hpp>
 #include <xo/tokenizer2/Token.hpp>
 #include <xo/reflect/TypeDescr.hpp>
 
@@ -65,6 +66,9 @@ namespace scm {
         void on_parsed_typedescr(Opaque data, TypeDescr td, ParserStateMachine * p_psm)  override {
             return I::on_parsed_typedescr(_dcast(data), td, p_psm);
         }
+        void on_parsed_type(Opaque data, obj<AType> type, ParserStateMachine * p_psm)  override {
+            return I::on_parsed_type(_dcast(data), type, p_psm);
+        }
         void on_parsed_formal(Opaque data, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm)  override {
             return I::on_parsed_formal(_dcast(data), param_name, param_type, p_psm);
         }
diff --git a/include/xo/reader2/ssm/RSyntaxStateMachine.hpp b/include/xo/reader2/ssm/RSyntaxStateMachine.hpp
index 33321d14..4ac4c791 100644
--- a/include/xo/reader2/ssm/RSyntaxStateMachine.hpp
+++ b/include/xo/reader2/ssm/RSyntaxStateMachine.hpp
@@ -71,6 +71,9 @@ public:
     void on_parsed_typedescr(TypeDescr td, ParserStateMachine * p_psm)  {
         return O::iface()->on_parsed_typedescr(O::data(), td, p_psm);
     }
+    void on_parsed_type(obj<AType> type, ParserStateMachine * p_psm)  {
+        return O::iface()->on_parsed_type(O::data(), type, p_psm);
+    }
     void on_parsed_formal(const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm)  {
         return O::iface()->on_parsed_formal(O::data(), param_name, param_type, p_psm);
     }
diff --git a/src/reader2/CMakeLists.txt b/src/reader2/CMakeLists.txt
index 15a7a338..8633f75a 100644
--- a/src/reader2/CMakeLists.txt
+++ b/src/reader2/CMakeLists.txt
@@ -92,6 +92,7 @@ xo_add_shared_library4(${SELF_LIB} ${PROJECT_NAME}Targets ${PROJECT_VERSION} 1 $
 xo_dependency(${SELF_LIB} xo_numeric)
 xo_dependency(${SELF_LIB} xo_procedure2)
 xo_dependency(${SELF_LIB} xo_gc)
+xo_dependency(${SELF_LIB} xo_type)
 xo_dependency(${SELF_LIB} xo_tokenizer2)
 xo_dependency(${SELF_LIB} xo_expression2)
 #xo_dependency(${SELF_LIB} reflect)
diff --git a/src/reader2/ISyntaxStateMachine_Any.cpp b/src/reader2/ISyntaxStateMachine_Any.cpp
index ccf69ca8..7d401163 100644
--- a/src/reader2/ISyntaxStateMachine_Any.cpp
+++ b/src/reader2/ISyntaxStateMachine_Any.cpp
@@ -53,6 +53,12 @@ ISyntaxStateMachine_Any::on_parsed_typedescr(Opaque, TypeDescr, ParserStateMachi
     _fatal();
 }
 
+auto
+ISyntaxStateMachine_Any::on_parsed_type(Opaque, obj<AType>, ParserStateMachine *)  -> void
+{
+    _fatal();
+}
+
 auto
 ISyntaxStateMachine_Any::on_parsed_formal(Opaque, const DUniqueString *, TypeDescr, ParserStateMachine *)  -> void
 {
diff --git a/src/reader2/ISyntaxStateMachine_DApplySsm.cpp b/src/reader2/ISyntaxStateMachine_DApplySsm.cpp
index f5cbb4e2..cd1a550d 100644
--- a/src/reader2/ISyntaxStateMachine_DApplySsm.cpp
+++ b/src/reader2/ISyntaxStateMachine_DApplySsm.cpp
@@ -43,6 +43,11 @@ namespace xo {
             self.on_parsed_typedescr(td, p_psm);
         }
         auto
+        ISyntaxStateMachine_DApplySsm::on_parsed_type(DApplySsm & self, obj<AType> type, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_type(type, p_psm);
+        }
+        auto
         ISyntaxStateMachine_DApplySsm::on_parsed_formal(DApplySsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm) -> void
         {
             self.on_parsed_formal(param_name, param_type, p_psm);
diff --git a/src/reader2/ISyntaxStateMachine_DDefineSsm.cpp b/src/reader2/ISyntaxStateMachine_DDefineSsm.cpp
index be766921..e038fac3 100644
--- a/src/reader2/ISyntaxStateMachine_DDefineSsm.cpp
+++ b/src/reader2/ISyntaxStateMachine_DDefineSsm.cpp
@@ -43,6 +43,11 @@ namespace xo {
             self.on_parsed_typedescr(td, p_psm);
         }
         auto
+        ISyntaxStateMachine_DDefineSsm::on_parsed_type(DDefineSsm & self, obj<AType> type, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_type(type, p_psm);
+        }
+        auto
         ISyntaxStateMachine_DDefineSsm::on_parsed_formal(DDefineSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm) -> void
         {
             self.on_parsed_formal(param_name, param_type, p_psm);
diff --git a/src/reader2/ISyntaxStateMachine_DExpectExprSsm.cpp b/src/reader2/ISyntaxStateMachine_DExpectExprSsm.cpp
index d505b427..911ec4d5 100644
--- a/src/reader2/ISyntaxStateMachine_DExpectExprSsm.cpp
+++ b/src/reader2/ISyntaxStateMachine_DExpectExprSsm.cpp
@@ -43,6 +43,11 @@ namespace xo {
             self.on_parsed_typedescr(td, p_psm);
         }
         auto
+        ISyntaxStateMachine_DExpectExprSsm::on_parsed_type(DExpectExprSsm & self, obj<AType> type, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_type(type, p_psm);
+        }
+        auto
         ISyntaxStateMachine_DExpectExprSsm::on_parsed_formal(DExpectExprSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm) -> void
         {
             self.on_parsed_formal(param_name, param_type, p_psm);
diff --git a/src/reader2/ISyntaxStateMachine_DExpectFormalArgSsm.cpp b/src/reader2/ISyntaxStateMachine_DExpectFormalArgSsm.cpp
index 50131470..1089d5ee 100644
--- a/src/reader2/ISyntaxStateMachine_DExpectFormalArgSsm.cpp
+++ b/src/reader2/ISyntaxStateMachine_DExpectFormalArgSsm.cpp
@@ -43,6 +43,11 @@ namespace xo {
             self.on_parsed_typedescr(td, p_psm);
         }
         auto
+        ISyntaxStateMachine_DExpectFormalArgSsm::on_parsed_type(DExpectFormalArgSsm & self, obj<AType> type, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_type(type, p_psm);
+        }
+        auto
         ISyntaxStateMachine_DExpectFormalArgSsm::on_parsed_formal(DExpectFormalArgSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm) -> void
         {
             self.on_parsed_formal(param_name, param_type, p_psm);
diff --git a/src/reader2/ISyntaxStateMachine_DExpectFormalArglistSsm.cpp b/src/reader2/ISyntaxStateMachine_DExpectFormalArglistSsm.cpp
index 982ce47a..b92e9655 100644
--- a/src/reader2/ISyntaxStateMachine_DExpectFormalArglistSsm.cpp
+++ b/src/reader2/ISyntaxStateMachine_DExpectFormalArglistSsm.cpp
@@ -43,6 +43,11 @@ namespace xo {
             self.on_parsed_typedescr(td, p_psm);
         }
         auto
+        ISyntaxStateMachine_DExpectFormalArglistSsm::on_parsed_type(DExpectFormalArglistSsm & self, obj<AType> type, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_type(type, p_psm);
+        }
+        auto
         ISyntaxStateMachine_DExpectFormalArglistSsm::on_parsed_formal(DExpectFormalArglistSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm) -> void
         {
             self.on_parsed_formal(param_name, param_type, p_psm);
diff --git a/src/reader2/ISyntaxStateMachine_DExpectQArraySsm.cpp b/src/reader2/ISyntaxStateMachine_DExpectQArraySsm.cpp
index 32d8bfd1..e205409f 100644
--- a/src/reader2/ISyntaxStateMachine_DExpectQArraySsm.cpp
+++ b/src/reader2/ISyntaxStateMachine_DExpectQArraySsm.cpp
@@ -43,6 +43,11 @@ namespace xo {
             self.on_parsed_typedescr(td, p_psm);
         }
         auto
+        ISyntaxStateMachine_DExpectQArraySsm::on_parsed_type(DExpectQArraySsm & self, obj<AType> type, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_type(type, p_psm);
+        }
+        auto
         ISyntaxStateMachine_DExpectQArraySsm::on_parsed_formal(DExpectQArraySsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm) -> void
         {
             self.on_parsed_formal(param_name, param_type, p_psm);
diff --git a/src/reader2/ISyntaxStateMachine_DExpectQListSsm.cpp b/src/reader2/ISyntaxStateMachine_DExpectQListSsm.cpp
index 2d24b697..0f64936e 100644
--- a/src/reader2/ISyntaxStateMachine_DExpectQListSsm.cpp
+++ b/src/reader2/ISyntaxStateMachine_DExpectQListSsm.cpp
@@ -43,6 +43,11 @@ namespace xo {
             self.on_parsed_typedescr(td, p_psm);
         }
         auto
+        ISyntaxStateMachine_DExpectQListSsm::on_parsed_type(DExpectQListSsm & self, obj<AType> type, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_type(type, p_psm);
+        }
+        auto
         ISyntaxStateMachine_DExpectQListSsm::on_parsed_formal(DExpectQListSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm) -> void
         {
             self.on_parsed_formal(param_name, param_type, p_psm);
diff --git a/src/reader2/ISyntaxStateMachine_DExpectQLiteralSsm.cpp b/src/reader2/ISyntaxStateMachine_DExpectQLiteralSsm.cpp
index 977b1194..bde94b6b 100644
--- a/src/reader2/ISyntaxStateMachine_DExpectQLiteralSsm.cpp
+++ b/src/reader2/ISyntaxStateMachine_DExpectQLiteralSsm.cpp
@@ -43,6 +43,11 @@ namespace xo {
             self.on_parsed_typedescr(td, p_psm);
         }
         auto
+        ISyntaxStateMachine_DExpectQLiteralSsm::on_parsed_type(DExpectQLiteralSsm & self, obj<AType> type, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_type(type, p_psm);
+        }
+        auto
         ISyntaxStateMachine_DExpectQLiteralSsm::on_parsed_formal(DExpectQLiteralSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm) -> void
         {
             self.on_parsed_formal(param_name, param_type, p_psm);
diff --git a/src/reader2/ISyntaxStateMachine_DExpectSymbolSsm.cpp b/src/reader2/ISyntaxStateMachine_DExpectSymbolSsm.cpp
index 3701069f..ebeaafe7 100644
--- a/src/reader2/ISyntaxStateMachine_DExpectSymbolSsm.cpp
+++ b/src/reader2/ISyntaxStateMachine_DExpectSymbolSsm.cpp
@@ -43,6 +43,11 @@ namespace xo {
             self.on_parsed_typedescr(td, p_psm);
         }
         auto
+        ISyntaxStateMachine_DExpectSymbolSsm::on_parsed_type(DExpectSymbolSsm & self, obj<AType> type, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_type(type, p_psm);
+        }
+        auto
         ISyntaxStateMachine_DExpectSymbolSsm::on_parsed_formal(DExpectSymbolSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm) -> void
         {
             self.on_parsed_formal(param_name, param_type, p_psm);
diff --git a/src/reader2/ISyntaxStateMachine_DExpectTypeSsm.cpp b/src/reader2/ISyntaxStateMachine_DExpectTypeSsm.cpp
index e83c591a..267810e2 100644
--- a/src/reader2/ISyntaxStateMachine_DExpectTypeSsm.cpp
+++ b/src/reader2/ISyntaxStateMachine_DExpectTypeSsm.cpp
@@ -43,6 +43,11 @@ namespace xo {
             self.on_parsed_typedescr(td, p_psm);
         }
         auto
+        ISyntaxStateMachine_DExpectTypeSsm::on_parsed_type(DExpectTypeSsm & self, obj<AType> type, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_type(type, p_psm);
+        }
+        auto
         ISyntaxStateMachine_DExpectTypeSsm::on_parsed_formal(DExpectTypeSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm) -> void
         {
             self.on_parsed_formal(param_name, param_type, p_psm);
diff --git a/src/reader2/ISyntaxStateMachine_DIfElseSsm.cpp b/src/reader2/ISyntaxStateMachine_DIfElseSsm.cpp
index fc28d9c9..fef959ca 100644
--- a/src/reader2/ISyntaxStateMachine_DIfElseSsm.cpp
+++ b/src/reader2/ISyntaxStateMachine_DIfElseSsm.cpp
@@ -43,6 +43,11 @@ namespace xo {
             self.on_parsed_typedescr(td, p_psm);
         }
         auto
+        ISyntaxStateMachine_DIfElseSsm::on_parsed_type(DIfElseSsm & self, obj<AType> type, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_type(type, p_psm);
+        }
+        auto
         ISyntaxStateMachine_DIfElseSsm::on_parsed_formal(DIfElseSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm) -> void
         {
             self.on_parsed_formal(param_name, param_type, p_psm);
diff --git a/src/reader2/ISyntaxStateMachine_DLambdaSsm.cpp b/src/reader2/ISyntaxStateMachine_DLambdaSsm.cpp
index 2ce18e6b..e131c12d 100644
--- a/src/reader2/ISyntaxStateMachine_DLambdaSsm.cpp
+++ b/src/reader2/ISyntaxStateMachine_DLambdaSsm.cpp
@@ -43,6 +43,11 @@ namespace xo {
             self.on_parsed_typedescr(td, p_psm);
         }
         auto
+        ISyntaxStateMachine_DLambdaSsm::on_parsed_type(DLambdaSsm & self, obj<AType> type, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_type(type, p_psm);
+        }
+        auto
         ISyntaxStateMachine_DLambdaSsm::on_parsed_formal(DLambdaSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm) -> void
         {
             self.on_parsed_formal(param_name, param_type, p_psm);
diff --git a/src/reader2/ISyntaxStateMachine_DParenSsm.cpp b/src/reader2/ISyntaxStateMachine_DParenSsm.cpp
index dcd49028..05f5d4cc 100644
--- a/src/reader2/ISyntaxStateMachine_DParenSsm.cpp
+++ b/src/reader2/ISyntaxStateMachine_DParenSsm.cpp
@@ -43,6 +43,11 @@ namespace xo {
             self.on_parsed_typedescr(td, p_psm);
         }
         auto
+        ISyntaxStateMachine_DParenSsm::on_parsed_type(DParenSsm & self, obj<AType> type, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_type(type, p_psm);
+        }
+        auto
         ISyntaxStateMachine_DParenSsm::on_parsed_formal(DParenSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm) -> void
         {
             self.on_parsed_formal(param_name, param_type, p_psm);
diff --git a/src/reader2/ISyntaxStateMachine_DProgressSsm.cpp b/src/reader2/ISyntaxStateMachine_DProgressSsm.cpp
index c9d1931c..f1c0e2cf 100644
--- a/src/reader2/ISyntaxStateMachine_DProgressSsm.cpp
+++ b/src/reader2/ISyntaxStateMachine_DProgressSsm.cpp
@@ -43,6 +43,11 @@ namespace xo {
             self.on_parsed_typedescr(td, p_psm);
         }
         auto
+        ISyntaxStateMachine_DProgressSsm::on_parsed_type(DProgressSsm & self, obj<AType> type, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_type(type, p_psm);
+        }
+        auto
         ISyntaxStateMachine_DProgressSsm::on_parsed_formal(DProgressSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm) -> void
         {
             self.on_parsed_formal(param_name, param_type, p_psm);
diff --git a/src/reader2/ISyntaxStateMachine_DQuoteSsm.cpp b/src/reader2/ISyntaxStateMachine_DQuoteSsm.cpp
index 9281d6f5..233819be 100644
--- a/src/reader2/ISyntaxStateMachine_DQuoteSsm.cpp
+++ b/src/reader2/ISyntaxStateMachine_DQuoteSsm.cpp
@@ -43,6 +43,11 @@ namespace xo {
             self.on_parsed_typedescr(td, p_psm);
         }
         auto
+        ISyntaxStateMachine_DQuoteSsm::on_parsed_type(DQuoteSsm & self, obj<AType> type, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_type(type, p_psm);
+        }
+        auto
         ISyntaxStateMachine_DQuoteSsm::on_parsed_formal(DQuoteSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm) -> void
         {
             self.on_parsed_formal(param_name, param_type, p_psm);
diff --git a/src/reader2/ISyntaxStateMachine_DSequenceSsm.cpp b/src/reader2/ISyntaxStateMachine_DSequenceSsm.cpp
index 5aa181bb..714a04f8 100644
--- a/src/reader2/ISyntaxStateMachine_DSequenceSsm.cpp
+++ b/src/reader2/ISyntaxStateMachine_DSequenceSsm.cpp
@@ -43,6 +43,11 @@ namespace xo {
             self.on_parsed_typedescr(td, p_psm);
         }
         auto
+        ISyntaxStateMachine_DSequenceSsm::on_parsed_type(DSequenceSsm & self, obj<AType> type, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_type(type, p_psm);
+        }
+        auto
         ISyntaxStateMachine_DSequenceSsm::on_parsed_formal(DSequenceSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm) -> void
         {
             self.on_parsed_formal(param_name, param_type, p_psm);
diff --git a/src/reader2/ISyntaxStateMachine_DToplevelSeqSsm.cpp b/src/reader2/ISyntaxStateMachine_DToplevelSeqSsm.cpp
index 698ccefc..e78c78c7 100644
--- a/src/reader2/ISyntaxStateMachine_DToplevelSeqSsm.cpp
+++ b/src/reader2/ISyntaxStateMachine_DToplevelSeqSsm.cpp
@@ -43,6 +43,11 @@ namespace xo {
             self.on_parsed_typedescr(td, p_psm);
         }
         auto
+        ISyntaxStateMachine_DToplevelSeqSsm::on_parsed_type(DToplevelSeqSsm & self, obj<AType> type, ParserStateMachine * p_psm) -> void
+        {
+            self.on_parsed_type(type, p_psm);
+        }
+        auto
         ISyntaxStateMachine_DToplevelSeqSsm::on_parsed_formal(DToplevelSeqSsm & self, const DUniqueString * param_name, TypeDescr param_type, ParserStateMachine * p_psm) -> void
         {
             self.on_parsed_formal(param_name, param_type, p_psm);
diff --git a/src/reader2/ParserStateMachine.cpp b/src/reader2/ParserStateMachine.cpp
index 125ca1dd..3c640332 100644
--- a/src/reader2/ParserStateMachine.cpp
+++ b/src/reader2/ParserStateMachine.cpp
@@ -439,6 +439,29 @@ namespace xo {
             this->capture_error(ssm_name, errmsg);
         }
 
+        void
+        ParserStateMachine::illegal_input_on_type(std::string_view ssm_name,
+                                                  obj<AType> type,
+                                                  std::string_view expect_str)
+        {
+            // TODO:
+            // - want to write error message using DArena
+            // - need something like log_streambuf and/or tostr() that's arena-aware
+
+            auto errmsg_string = tostr("Unexpected type for parsing state",
+                                       xtag("type", type),
+                                       xtag("expecting", expect_str),
+                                       xtag("ssm", ssm_name),
+                                       xtag("via", "ParserStateMachine::illegal_input_on_type"));
+
+            assert(expr_alloc_);
+
+            auto errmsg = DString::from_view(expr_alloc_,
+                                             std::string_view(errmsg_string));
+
+            this->capture_error(ssm_name, errmsg);
+        }
+
         void
         ParserStateMachine::illegal_parsed_formal(std::string_view ssm_name,
                                                   const DUniqueString * param_name,