diff --git a/ast/ast_dumper.cpp b/ast/ast_dumper.cpp
index 6c26c09..47adbd2 100644
--- a/ast/ast_dumper.cpp
+++ b/ast/ast_dumper.cpp
@@ -116,18 +116,14 @@ bool ast_dumper::visit_code_block(code_block* node) {
 
 bool ast_dumper::visit_parameter(parameter* node) {
     dump_indent();
-    std::cout << "parameter";
+    std::cout << "parameter " << node->get_parameter_name();
     std::cout << format_location(node->get_location());
-    push_indent();
-    if (!node->get_default_value()) {
-        set_last();
-    }
-    node->get_parameter_name()->accept(this);
     if (node->get_default_value()) {
+        push_indent();
         set_last();
         node->get_default_value()->accept(this);
+        pop_indent();
     }
-    pop_indent();
     return true;
 }
 
diff --git a/ast/ast_visitor.cpp b/ast/ast_visitor.cpp
index e641856..7284724 100644
--- a/ast/ast_visitor.cpp
+++ b/ast/ast_visitor.cpp
@@ -66,7 +66,6 @@ bool ast_visitor::visit_code_block(code_block* node) {
 }
 
 bool ast_visitor::visit_parameter(parameter* node) {
-    node->get_parameter_name()->accept(this);
     if (node->get_default_value()) {
         node->get_default_value()->accept(this);
     }
diff --git a/ast/nasal_new_ast.cpp b/ast/nasal_new_ast.cpp
index c6d7c16..4ad8131 100644
--- a/ast/nasal_new_ast.cpp
+++ b/ast/nasal_new_ast.cpp
@@ -83,9 +83,6 @@ void code_block::accept(ast_visitor* visitor) {
 }
 
 parameter::~parameter() {
-    if (name) {
-        delete name;
-    }
     if (default_value) {
         delete default_value;
     }
diff --git a/ast/nasal_new_ast.h b/ast/nasal_new_ast.h
index 58ec85d..a16d6a9 100644
--- a/ast/nasal_new_ast.h
+++ b/ast/nasal_new_ast.h
@@ -51,14 +51,15 @@ class multi_identifier;
 class code_block;
 class if_expr;
 
-class ast_abstract_node {
+class expr {
 protected:
     span nd_loc;
     expr_type nd_type;
 
 public:
-    ast_abstract_node(const span& location, expr_type node_type):
+    expr(const span& location, expr_type node_type):
         nd_loc(location), nd_type(node_type) {}
+    ~expr() = default;
     void set_begin(u32 line, u32 column) {
         nd_loc.begin_line = line;
         nd_loc.begin_column = column;
@@ -69,15 +70,7 @@ public:
         nd_loc.end_line = location.end_line;
         nd_loc.end_column = location.end_column;
     }
-    virtual void accept(ast_visitor*) = 0;
-};
-
-class expr:public ast_abstract_node {
-public:
-    expr(const span& location, expr_type node_type):
-        ast_abstract_node(location, node_type) {}
-    ~expr() = default;
-    void accept(ast_visitor*);
+    virtual void accept(ast_visitor*);
 };
 
 class null_expr:public expr {
@@ -227,19 +220,19 @@ public:
 
 private:
     param_type type;
-    identifier* name;
+    std::string name;
     expr* default_value;
 
 public:
     parameter(const span& location):
         expr(location, expr_type::ast_param),
-        name(nullptr), default_value(nullptr) {}
+        name(""), default_value(nullptr) {}
     ~parameter();
     void set_parameter_type(param_type pt) {type = pt;}
-    void set_parameter_name(identifier* node) {name = node;}
+    void set_parameter_name(const std::string& pname) {name = pname;}
     void set_default_value(expr* node) {default_value = node;}
     param_type get_type() {return type;}
-    identifier* get_parameter_name() {return name;}
+    const std::string& get_parameter_name() const {return name;}
     expr* get_default_value() {return default_value;}
     void accept(ast_visitor*) override;
 };
diff --git a/ast/nasal_new_parse.cpp b/ast/nasal_new_parse.cpp
index e175910..a306be5 100644
--- a/ast/nasal_new_parse.cpp
+++ b/ast/nasal_new_parse.cpp
@@ -284,16 +284,16 @@ void parse::params(function* func_node) {
     match(tok::lcurve);
     while(!lookahead(tok::rcurve)) {
         auto param = new parameter(toks[ptr].loc);
-        param->set_parameter_name(id());
-        if (lookahead(tok::eq) || lookahead(tok::ellipsis)) {
-            if (lookahead(tok::eq)) {
-                match(tok::eq);
-                param->set_parameter_type(parameter::param_type::default_parameter);
-                param->set_default_value(calc());
-            } else {
-                match(tok::ellipsis);
-                param->set_parameter_type(parameter::param_type::dynamic_parameter);
-            }
+        auto id_node = id();
+        param->set_parameter_name(id_node->get_name());
+        delete id_node;
+        if (lookahead(tok::eq)) {
+            match(tok::eq);
+            param->set_parameter_type(parameter::param_type::default_parameter);
+            param->set_default_value(calc());
+        } else if (lookahead(tok::ellipsis)) {
+            match(tok::ellipsis);
+            param->set_parameter_type(parameter::param_type::dynamic_parameter);
         } else {
             param->set_parameter_type(parameter::param_type::normal_parameter);
         }
diff --git a/stl/lib.nas b/stl/lib.nas
index b7f734e..07e037f 100644
--- a/stl/lib.nas
+++ b/stl/lib.nas
@@ -222,8 +222,7 @@ var isfunc=func(f){
 }
 
 var isghost=func(g){
-    die("this runtime has no ghost object");
-    return 0;
+    return typeof(f)=="obj";
 }
 
 var ishash=func(h){