diff --git a/sprout/algorithm/string/join.hpp b/sprout/algorithm/string/join.hpp
index acb665c5..eb9c3842 100644
--- a/sprout/algorithm/string/join.hpp
+++ b/sprout/algorithm/string/join.hpp
@@ -12,7 +12,7 @@
 #include <sprout/range/adaptor/size_enumed.hpp>
 #include <sprout/range/algorithm/lower_bound.hpp>
 #include <sprout/range/numeric/partial_sum.hpp>
-#include <sprout/weed/traits/type/is_c_str.hpp>
+#include <sprout/type_traits/is_c_str.hpp>
 
 namespace sprout {
 	namespace algorithm {
@@ -22,7 +22,7 @@ namespace sprout {
 			template<typename String>
 			struct string_size<
 				String,
-				typename std::enable_if<sprout::weed::traits::is_c_str<String>::value>::type
+				typename std::enable_if<sprout::is_c_str<String>::value>::type
 			>
 				: public std::integral_constant<
 					typename sprout::container_traits<String>::size_type,
@@ -32,7 +32,7 @@ namespace sprout {
 			template<typename String>
 			struct string_size<
 				String,
-				typename std::enable_if<!sprout::weed::traits::is_c_str<String>::value>::type
+				typename std::enable_if<!sprout::is_c_str<String>::value>::type
 			>
 				: public std::integral_constant<
 					typename sprout::container_traits<String>::size_type,
@@ -42,7 +42,7 @@ namespace sprout {
 
 			template<
 				typename String,
-				typename sprout::enabler_if<sprout::weed::traits::is_c_str<String>::value>::type = sprout::enabler
+				typename sprout::enabler_if<sprout::is_c_str<String>::value>::type = sprout::enabler
 			>
 			inline SPROUT_CONSTEXPR typename sprout::container_traits<String>::difference_type
 			str_size(String const& str) {
@@ -50,7 +50,7 @@ namespace sprout {
 			}
 			template<
 				typename String,
-				typename sprout::enabler_if<!sprout::weed::traits::is_c_str<String>::value>::type = sprout::enabler
+				typename sprout::enabler_if<!sprout::is_c_str<String>::value>::type = sprout::enabler
 			>
 			inline SPROUT_CONSTEXPR typename sprout::container_traits<String>::difference_type
 			str_size(String const& str) {
diff --git a/sprout/io.hpp b/sprout/io.hpp
index 97d5e5f8..d2fc7a4b 100644
--- a/sprout/io.hpp
+++ b/sprout/io.hpp
@@ -14,7 +14,7 @@
 #include <sprout/utility/enabler_if.hpp>
 #include <sprout/range/algorithm/lower_bound.hpp>
 #include <sprout/range/numeric/partial_sum.hpp>
-#include <sprout/weed/traits/type/is_char_type.hpp>
+#include <sprout/type_traits/is_char_type.hpp>
 #include <sprout/detail/param_at.hpp>
 #include HDR_ALGORITHM_SSCRISK_CEL_OR_SPROUT
 
@@ -676,7 +676,7 @@ namespace sprout {
 			typename Elem, std::size_t N, typename T,
 			typename sprout::enabler_if<
 				std::is_integral<T>::value
-					&& !sprout::weed::traits::is_char_type<T>::value
+					&& !sprout::is_char_type<T>::value
 			>::type = sprout::enabler
 		>
 		inline SPROUT_CONSTEXPR auto
@@ -697,7 +697,7 @@ namespace sprout {
 		}
 		template<
 			typename Elem, std::size_t N, typename T,
-			typename sprout::enabler_if<sprout::weed::traits::is_char_type<T>::value>::type = sprout::enabler
+			typename sprout::enabler_if<sprout::is_char_type<T>::value>::type = sprout::enabler
 		>
 		inline SPROUT_CONSTEXPR auto
 		eval(sprout::io::format_holder<T> const& holder)
diff --git a/sprout/iterator/counting_iterator.hpp b/sprout/iterator/counting_iterator.hpp
index 727adf7e..dbde1e97 100644
--- a/sprout/iterator/counting_iterator.hpp
+++ b/sprout/iterator/counting_iterator.hpp
@@ -1,7 +1,7 @@
 #ifndef SPROUT_ITERATOR_COUNTING_ITERATOR_HPP
 #define SPROUT_ITERATOR_COUNTING_ITERATOR_HPP
 
-#include <cstddef>
+#include <limits>
 #include <iterator>
 #include <utility>
 #include <type_traits>
@@ -34,7 +34,9 @@ namespace sprout {
 		value_type current_;
 	private:
 	public:
-		counting_iterator() = default;
+		SPROUT_CONSTEXPR counting_iterator()
+			: current_(std::numeric_limits<value_type>::max())
+		{}
 		counting_iterator(counting_iterator const&) = default;
 		explicit SPROUT_CONSTEXPR counting_iterator(value_type const& v)
 			: current_(v)
diff --git a/sprout/pit.hpp b/sprout/pit.hpp
index f21914c9..8a80edb1 100644
--- a/sprout/pit.hpp
+++ b/sprout/pit.hpp
@@ -10,6 +10,7 @@
 #include <sprout/iterator.hpp>
 #include <sprout/iterator/value_iterator.hpp>
 #include <sprout/utility/forward.hpp>
+#include <sprout/array.hpp>
 
 namespace sprout {
 	//
@@ -210,6 +211,20 @@ namespace sprout {
 			> type;
 		};
 	};
+
+	//
+	// blank
+	//
+	struct blank {};
+
+	//
+	// blank_pit
+	//
+	template<std::size_t N>
+	inline SPROUT_CONSTEXPR sprout::pit<sprout::array<sprout::blank, N> >
+	blank_pit() {
+		return sprout::pit<sprout::array<sprout::blank, N> >();
+	}
 }	// namespace sprout
 
 namespace std {
diff --git a/sprout/range/adaptor.hpp b/sprout/range/adaptor.hpp
index 7f9d5938..56ee0a14 100644
--- a/sprout/range/adaptor.hpp
+++ b/sprout/range/adaptor.hpp
@@ -4,6 +4,7 @@
 #include <sprout/config.hpp>
 #include <sprout/range/adaptor/copied.hpp>
 #include <sprout/range/adaptor/transformed.hpp>
+#include <sprout/range/adaptor/counting.hpp>
 #include <sprout/range/adaptor/size_enumed.hpp>
 #include <sprout/range/adaptor/sinusoidal.hpp>
 
diff --git a/sprout/range/adaptor/counting.hpp b/sprout/range/adaptor/counting.hpp
index ccd2d6c7..c6217248 100644
--- a/sprout/range/adaptor/counting.hpp
+++ b/sprout/range/adaptor/counting.hpp
@@ -1,7 +1,6 @@
 #ifndef SPROUT_RANGE_ADAPTOR_COUNTING_HPP
 #define SPROUT_RANGE_ADAPTOR_COUNTING_HPP
 
-#include <limits>
 #include <type_traits>
 #include <sprout/config.hpp>
 #include <sprout/pit.hpp>
@@ -85,7 +84,7 @@ namespace sprout {
 			explicit SPROUT_CONSTEXPR counting_range(value_type const& first)
 				: base_type(
 					iterator(first),
-					iterator(std::numeric_limits<value_type>::max())
+					iterator()
 					)
 			{}
 			SPROUT_CONSTEXPR counting_range(
diff --git a/sprout/type_traits.hpp b/sprout/type_traits.hpp
index 45d0d21e..621e9d11 100644
--- a/sprout/type_traits.hpp
+++ b/sprout/type_traits.hpp
@@ -4,9 +4,10 @@
 #include <sprout/config.hpp>
 #include <sprout/type_traits/is_int.hpp>
 #include <sprout/type_traits/is_uint.hpp>
+#include <sprout/type_traits/is_char_type.hpp>
+#include <sprout/type_traits/is_c_str.hpp>
 #include <sprout/type_traits/lvalue_reference.hpp>
 #include <sprout/type_traits/const_reference.hpp>
 #include <sprout/type_traits/has_xxx.hpp>
-#include <sprout/type_traits/inherit_if_xxx.hpp>
 
 #endif	// #ifndef SPROUT_TYPE_TRAITS_HPP
diff --git a/sprout/type_traits/is_c_str.hpp b/sprout/type_traits/is_c_str.hpp
new file mode 100644
index 00000000..cb7859cf
--- /dev/null
+++ b/sprout/type_traits/is_c_str.hpp
@@ -0,0 +1,61 @@
+#ifndef SPROUT_TYPE_TRAITS_IS_C_STR_HPP
+#define SPROUT_TYPE_TRAITS_IS_C_STR_HPP
+
+#include <type_traits>
+#include <sprout/config.hpp>
+
+namespace sprout {
+	//
+	// is_c_str
+	//
+	template<typename T>
+	struct is_c_str
+		: public std::false_type
+	{};
+	template<typename T>
+	struct is_c_str<T const>
+		: public sprout::is_c_str<T>
+	{};
+	template<typename T>
+	struct is_c_str<T volatile>
+		: public sprout::is_c_str<T>
+	{};
+	template<typename T>
+	struct is_c_str<T const volatile>
+		: public sprout::is_c_str<T>
+	{};
+	template<std::size_t N>
+	struct is_c_str<char[N]>
+		: public std::true_type
+	{};
+	template<std::size_t N>
+	struct is_c_str<wchar_t[N]>
+		: public std::true_type
+	{};
+	template<std::size_t N>
+	struct is_c_str<char16_t[N]>
+		: public std::true_type
+	{};
+	template<std::size_t N>
+	struct is_c_str<char32_t[N]>
+		: public std::true_type
+	{};
+	template<std::size_t N>
+	struct is_c_str<char const[N]>
+		: public std::true_type
+	{};
+	template<std::size_t N>
+	struct is_c_str<wchar_t const[N]>
+		: public std::true_type
+	{};
+	template<std::size_t N>
+	struct is_c_str<char16_t const[N]>
+		: public std::true_type
+	{};
+	template<std::size_t N>
+	struct is_c_str<char32_t const[N]>
+		: public std::true_type
+	{};
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_TYPE_TRAITS_IS_C_STR_HPP
diff --git a/sprout/type_traits/is_char_type.hpp b/sprout/type_traits/is_char_type.hpp
new file mode 100644
index 00000000..7c9e3486
--- /dev/null
+++ b/sprout/type_traits/is_char_type.hpp
@@ -0,0 +1,45 @@
+#ifndef SPROUT_TYPE_TRAITS_IS_CHAR_TYPE_HPP
+#define SPROUT_TYPE_TRAITS_IS_CHAR_TYPE_HPP
+
+#include <type_traits>
+#include <sprout/config.hpp>
+
+namespace sprout {
+	//
+	// is_char_type
+	//
+	template<typename T>
+	struct is_char_type
+		: public std::false_type
+	{};
+	template<typename T>
+	struct is_char_type<T const>
+		: public sprout::is_char_type<T>
+	{};
+	template<typename T>
+	struct is_char_type<T volatile>
+		: public sprout::is_char_type<T>
+	{};
+	template<typename T>
+	struct is_char_type<T const volatile>
+		: public sprout::is_char_type<T>
+	{};
+	template<>
+	struct is_char_type<char>
+		: public std::true_type
+	{};
+	template<>
+	struct is_char_type<wchar_t>
+		: public std::true_type
+	{};
+	template<>
+	struct is_char_type<char16_t>
+		: public std::true_type
+	{};
+	template<>
+	struct is_char_type<char32_t>
+		: public std::true_type
+	{};
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_TYPE_TRAITS_IS_CHAR_TYPE_HPP
diff --git a/sprout/weed/traits/type/is_c_str.hpp b/sprout/weed/traits/type/is_c_str.hpp
index 24bbf5f7..9ba5b71b 100644
--- a/sprout/weed/traits/type/is_c_str.hpp
+++ b/sprout/weed/traits/type/is_c_str.hpp
@@ -1,8 +1,8 @@
 #ifndef SPROUT_WEED_TRAITS_TYPE_IS_C_STR_HPP
 #define SPROUT_WEED_TRAITS_TYPE_IS_C_STR_HPP
 
-#include <type_traits>
 #include <sprout/config.hpp>
+#include <sprout/type_traits/is_c_str.hpp>
 
 namespace sprout {
 	namespace weed {
@@ -12,51 +12,7 @@ namespace sprout {
 			//
 			template<typename T>
 			struct is_c_str
-				: public std::false_type
-			{};
-			template<typename T>
-			struct is_c_str<T const>
-				: public sprout::weed::traits::is_c_str<T>
-			{};
-			template<typename T>
-			struct is_c_str<T volatile>
-				: public sprout::weed::traits::is_c_str<T>
-			{};
-			template<typename T>
-			struct is_c_str<T const volatile>
-				: public sprout::weed::traits::is_c_str<T>
-			{};
-			template<std::size_t N>
-			struct is_c_str<char[N]>
-				: public std::true_type
-			{};
-			template<std::size_t N>
-			struct is_c_str<wchar_t[N]>
-				: public std::true_type
-			{};
-			template<std::size_t N>
-			struct is_c_str<char16_t[N]>
-				: public std::true_type
-			{};
-			template<std::size_t N>
-			struct is_c_str<char32_t[N]>
-				: public std::true_type
-			{};
-			template<std::size_t N>
-			struct is_c_str<char const[N]>
-				: public std::true_type
-			{};
-			template<std::size_t N>
-			struct is_c_str<wchar_t const[N]>
-				: public std::true_type
-			{};
-			template<std::size_t N>
-			struct is_c_str<char16_t const[N]>
-				: public std::true_type
-			{};
-			template<std::size_t N>
-			struct is_c_str<char32_t const[N]>
-				: public std::true_type
+				: public sprout::is_c_str<T>
 			{};
 		}	// namespace traits
 	}	// namespace weed
diff --git a/sprout/weed/traits/type/is_char_type.hpp b/sprout/weed/traits/type/is_char_type.hpp
index b0e8e8b3..c23d109a 100644
--- a/sprout/weed/traits/type/is_char_type.hpp
+++ b/sprout/weed/traits/type/is_char_type.hpp
@@ -1,8 +1,8 @@
 #ifndef SPROUT_WEED_TRAITS_TYPE_IS_CHAR_TYPE_HPP
 #define SPROUT_WEED_TRAITS_TYPE_IS_CHAR_TYPE_HPP
 
-#include <type_traits>
 #include <sprout/config.hpp>
+#include <sprout/type_traits/is_char_type.hpp>
 
 namespace sprout {
 	namespace weed {
@@ -12,35 +12,7 @@ namespace sprout {
 			//
 			template<typename T>
 			struct is_char_type
-				: public std::false_type
-			{};
-			template<typename T>
-			struct is_char_type<T const>
-				: public sprout::weed::traits::is_char_type<T>
-			{};
-			template<typename T>
-			struct is_char_type<T volatile>
-				: public sprout::weed::traits::is_char_type<T>
-			{};
-			template<typename T>
-			struct is_char_type<T const volatile>
-				: public sprout::weed::traits::is_char_type<T>
-			{};
-			template<>
-			struct is_char_type<char>
-				: public std::true_type
-			{};
-			template<>
-			struct is_char_type<wchar_t>
-				: public std::true_type
-			{};
-			template<>
-			struct is_char_type<char16_t>
-				: public std::true_type
-			{};
-			template<>
-			struct is_char_type<char32_t>
-				: public std::true_type
+				: public sprout::is_char_type<T>
 			{};
 		}	// namespace traits
 	}	// namespace weed