diff --git a/version3.0/nasal.ebnf b/version3.0/nasal.ebnf
index f7bf508..d5d0aa2 100644
--- a/version3.0/nasal.ebnf
+++ b/version3.0/nasal.ebnf
@@ -23,7 +23,7 @@ function::=
     func argument_list expressions
 ;
 argument_list::=
-    '(' [{id ','} ([id '...']|{id '=' calculation ','})] ')'
+    '(' [{id ','} ([id '...']|{id '=' scalar ','})] ')'
 ;
 expr::=
     definition
diff --git a/version3.0/nasal_enum.h b/version3.0/nasal_enum.h
index 06350bf..ed4fec5 100644
--- a/version3.0/nasal_enum.h
+++ b/version3.0/nasal_enum.h
@@ -14,6 +14,7 @@ enum token_type
     tok_left_brace,tok_right_brace,
     tok_semi,tok_and,tok_or,tok_comma,tok_dot,tok_ellipsis,tok_quesmark,
     tok_colon,tok_add,tok_sub,tok_mult,tok_div,tok_link,tok_not,
+    tok_equal,
     tok_add_equal,tok_sub_equal,tok_mult_equal,tok_div_equal,tok_link_equal,
     tok_cmp_equal,tok_cmp_not_equal,tok_less_than,tok_greater_than,tok_less_equal,tok_greater_equal
 };
@@ -23,7 +24,7 @@ enum ast_node
     ast_null=0,ast_root,ast_block,
     ast_nil,ast_number,ast_string,ast_identifier,ast_function,ast_hash,ast_vector,
     ast_hashmember,
-    ast_args,
+    ast_args,ast_default_arg,ast_dynamic_id,
     ast_and,ast_or,
     ast_equal,ast_add_equal,ast_sub_equal,ast_mult_equal,ast_div_equal,ast_link_equal,
     ast_cmp_equal,ast_cmp_not_equal,ast_less_than,ast_less_equal,ast_greater_than,ast_greater_equal,
@@ -48,9 +49,10 @@ enum parse_error
     lack_comma,
     lack_colon,
     lack_scalar,
+    lack_identifier,
 };
 
-void error_info(int line,int error_type)
+void error_info(int line,int error_type,std::string error_str="")
 {
     std::string info=">> [parse] error: line ";
     std::string detail;
@@ -58,17 +60,18 @@ void error_info(int line,int error_type)
     switch(error_type)
     {
         case unknown:           detail="unknown error.";                    break;
-        case error_token:       detail="this token should not exist here."; break;
+        case error_token:       detail="error token \'"+error_str+"\'";     break;
         case lack_id:           detail="lack identifier.";                  break;
         case lack_left_curve:   detail="lack \'(\'.";                       break;
         case lack_right_curve:  detail="lack \')\'.";                       break;
-        case lack_left_bracket: detail="lack left bracket.";                break;
-        case lack_left_brace:   detail="lack left brace.";                  break;
-        case lack_right_brace:  detail="lack right brace.";                 break;
-        case lack_semi:         detail="lack \';\' here.";                  break;
-        case lack_comma:        detail="lack comma.";                       break;
-        case lack_colon:        detail="lack colon.";                       break;
-        case lack_scalar:       detail="lack scalar";                       break;
+        case lack_left_bracket: detail="lack \'[\'.";                       break;
+        case lack_left_brace:   detail="lack \'{\'.";                       break;
+        case lack_right_brace:  detail="lack \'}\'.";                       break;
+        case lack_semi:         detail="lack \';\'.";                       break;
+        case lack_comma:        detail="lack \',\'.";                       break;
+        case lack_colon:        detail="lack \':\'.";                       break;
+        case lack_scalar:       detail="lack scalar.";                      break;
+        case lack_identifier:   detail="lack identifier.";                  break;
     }
     std::cout<<detail<<std::endl;
     return;
diff --git a/version3.0/nasal_lexer.h b/version3.0/nasal_lexer.h
index 7e494aa..7d95c5a 100644
--- a/version3.0/nasal_lexer.h
+++ b/version3.0/nasal_lexer.h
@@ -15,7 +15,7 @@
 #define IS_NOTE_HEAD(c)       (c=='#')
 
 #ifndef TOKEN_TABLE_SIZE
-#define TOKEN_TABLE_SIZE 44
+#define TOKEN_TABLE_SIZE 45
 struct token_table
 {
     std::string str;
@@ -55,6 +55,7 @@ struct token_table
     {"/"       ,tok_div          },
     {"~"       ,tok_link         },
     {"!"       ,tok_not          },
+	{"="       ,tok_equal        },
     {"+="      ,tok_add_equal    },
     {"-="      ,tok_sub_equal    },
     {"*="      ,tok_mult_equal   },
diff --git a/version3.0/nasal_parse.h b/version3.0/nasal_parse.h
index 17edc54..6010a6a 100644
--- a/version3.0/nasal_parse.h
+++ b/version3.0/nasal_parse.h
@@ -227,7 +227,6 @@ nasal_ast nasal_parse::func_gen()
     if(tok_list[ptr].type==tok_left_curve)
     {
         node.add_child(args_list_gen());
-        ++error;
         ++ptr;
     }
     if(ptr>=tok_list_size)
@@ -241,13 +240,52 @@ nasal_ast nasal_parse::func_gen()
 }
 nasal_ast nasal_parse::args_list_gen()
 {
+    int last_id_line;
     nasal_ast node;
     node.set_line(tok_list[ptr].line);
     node.set_type(ast_args);
-    ++ptr;
     while(ptr<tok_list_size && tok_list[ptr].type!=tok_right_curve)
     {
-        ;
+        nasal_ast tmp;
+        ++ptr;
+        if(tok_list[ptr].type!=tok_identifier)
+        {
+            ++error;
+            error_info(tok_list[ptr].line,lack_identifier);
+            return node;
+        }
+        tmp=id_gen();
+        last_id_line=tmp.get_line();
+        ++ptr;
+        if(ptr<tok_list_size && (tok_list[ptr].type==tok_equal || tok_list[ptr].type==tok_ellipsis))
+        {
+            nasal_ast special_arg;
+            special_arg.set_line(tok_list[ptr].line);
+            if(tok_list[ptr].type==tok_equal)
+            {
+                special_arg.add_child(tmp);
+                ++ptr;
+                special_arg.add_child(scalar());
+            }
+            else
+            {
+                special_arg=tmp;
+                special_arg.set_type(ast_dynamic_id);
+            }
+            node.add_child(special_arg);
+        }
+        else
+        {
+            --ptr;
+            node.add_child(tmp);
+        }
+        ++ptr;
+        if(ptr>=tok_list_size || (tok_list[ptr].type!=tok_comma && tok_list[ptr].type!=tok_right_curve))
+        {
+            ++error;
+            error_info(last_id_line,lack_comma);
+            --ptr;
+        }
     }
     return node;
 }
@@ -276,7 +314,7 @@ nasal_ast nasal_parse::expr()
         case tok_break:    node=break_expr();    break;
         case tok_return:   node=return_expr();   break;
         case tok_semi:     --ptr;                break;
-        default: error_info(tok_list[ptr].line,error_token);++error;break;
+        default: error_info(tok_list[ptr].line,error_token,tok_list[ptr].str);++error;break;
     }
     return node;
 }
@@ -427,8 +465,7 @@ nasal_ast nasal_parse::additive_expr()
 nasal_ast nasal_parse::multive_expr()
 {
     nasal_ast node;
-    if(tok_list[ptr].type==tok_sub || tok_list[ptr].type==tok_not)
-        node=unary();
+    node=(tok_list[ptr].type==tok_sub || tok_list[ptr].type==tok_not)?unary():scalar();
     ++ptr;
     while(ptr<tok_list_size && (tok_list[ptr].type==tok_mult || tok_list[ptr].type==tok_div))
     {
@@ -441,10 +478,8 @@ nasal_ast nasal_parse::multive_expr()
         }
         tmp.add_child(node);
         ++ptr;
-        if(ptr<tok_list_size && (tok_list[ptr].type==tok_sub || tok_list[ptr].type==tok_not))
-            tmp.add_child(unary());
-        else if(ptr<tok_list_size && tok_list[ptr].type!=tok_sub && tok_list[ptr].type!=tok_not)
-            tmp.add_child(scalar());
+        if(ptr<tok_list_size)
+            tmp.add_child((tok_list[ptr].type==tok_sub || tok_list[ptr].type==tok_not)?unary():scalar());
         node=tmp;
         ++ptr;
     }