diff --git a/include/fast_io_dsal/impl/list.h b/include/fast_io_dsal/impl/list.h
index d395e386..3a302749 100644
--- a/include/fast_io_dsal/impl/list.h
+++ b/include/fast_io_dsal/impl/list.h
@@ -605,11 +605,17 @@ class list
 		return const_reverse_iterator({__builtin_addressof(imp)});
 	}
 
+#if __has_cpp_attribute(__gnu__::__pure__)
+	[[__gnu__::__pure__]]
+#endif
 	[[nodiscard]] inline constexpr bool empty() const noexcept
 	{
 		return imp.next == __builtin_addressof(imp);
 	}
 
+#if __has_cpp_attribute(__gnu__::__pure__)
+	[[__gnu__::__pure__]]
+#endif
 	[[nodiscard]] inline constexpr bool is_empty() const noexcept
 	{
 		return imp.next == __builtin_addressof(imp);
@@ -908,9 +914,9 @@ class list
 
 	inline constexpr list(list &&other) noexcept
 		: imp(other.imp)
-		  #if 0
+#if 0
 		  , allochdl(std::move(other.allochdl))
-		  #endif
+#endif
 	{
 		auto prev = static_cast<::fast_io::containers::details::list_node_common *>(imp.prev);
 		auto next = static_cast<::fast_io::containers::details::list_node_common *>(imp.next);
@@ -924,9 +930,9 @@ class list
 		{
 			this->destroy();
 			imp = other.imp;
-			#if 0
+#if 0
 			allochdl = ::std::move(other.allochdl);
-			#endif
+#endif
 			auto prev = static_cast<::fast_io::containers::details::list_node_common *>(imp.prev);
 			auto next = static_cast<::fast_io::containers::details::list_node_common *>(imp.next);
 			next->prev = prev->next = __builtin_addressof(imp);
diff --git a/include/fast_io_dsal/impl/queue.h b/include/fast_io_dsal/impl/queue.h
index 07e27dbf..7f86ec85 100644
--- a/include/fast_io_dsal/impl/queue.h
+++ b/include/fast_io_dsal/impl/queue.h
@@ -69,6 +69,10 @@ class queue
 		return container.back_unchecked();
 	}
 
+#if __has_cpp_attribute(__gnu__::__pure__)
+	[[__gnu__::__pure__]]
+#endif
+	[[nodiscard]]
 	inline constexpr bool empty() const noexcept
 	{
 		if constexpr (requires() {
@@ -83,11 +87,19 @@ class queue
 		}
 	}
 
+#if __has_cpp_attribute(__gnu__::__pure__)
+	[[__gnu__::__pure__]]
+#endif
+	[[nodiscard]]
 	inline constexpr bool is_empty() const noexcept
 	{
 		return container.is_empty();
 	}
 
+#if __has_cpp_attribute(__gnu__::__pure__)
+	[[__gnu__::__pure__]]
+#endif
+	[[nodiscard]]
 	inline constexpr size_type size() const noexcept
 		requires(requires() {
 			container.size();
@@ -95,6 +107,7 @@ class queue
 	{
 		return container.size();
 	}
+
 	inline constexpr void push(value_type const &value)
 	{
 		container.push_back(value);
diff --git a/include/fast_io_dsal/impl/stack.h b/include/fast_io_dsal/impl/stack.h
index 5fab80c1..8773f90b 100644
--- a/include/fast_io_dsal/impl/stack.h
+++ b/include/fast_io_dsal/impl/stack.h
@@ -87,6 +87,10 @@ class stack
 		}
 	}
 
+#if __has_cpp_attribute(__gnu__::__pure__)
+	[[__gnu__::__pure__]]
+#endif
+	[[nodiscard]]
 	inline constexpr bool empty() const noexcept
 	{
 		if constexpr (requires() {
@@ -101,11 +105,19 @@ class stack
 		}
 	}
 
+#if __has_cpp_attribute(__gnu__::__pure__)
+	[[__gnu__::__pure__]]
+#endif
+	[[nodiscard]]
 	inline constexpr bool is_empty() const noexcept
 	{
 		return container.is_empty();
 	}
 
+#if __has_cpp_attribute(__gnu__::__pure__)
+	[[__gnu__::__pure__]]
+#endif
+	[[nodiscard]]
 	inline constexpr size_type size() const noexcept
 		requires(requires() {
 			container.size();
@@ -113,6 +125,7 @@ class stack
 	{
 		return container.size();
 	}
+
 	inline constexpr void push(value_type const &value)
 	{
 		if constexpr (requires() {
diff --git a/include/fast_io_dsal/impl/string.h b/include/fast_io_dsal/impl/string.h
index 5f4eedf7..057e2309 100644
--- a/include/fast_io_dsal/impl/string.h
+++ b/include/fast_io_dsal/impl/string.h
@@ -218,20 +218,33 @@ class basic_string FAST_IO_TRIVIALLY_RELOCATABLE_IF_ELIGIBLE
 		return imp.begin_ptr;
 	}
 
+#if __has_cpp_attribute(__gnu__::__pure__)
+	[[__gnu__::__pure__]]
+#endif
+	[[nodiscard]]
 	inline constexpr bool is_empty() const noexcept
 	{
 		return imp.begin_ptr == imp.curr_ptr;
 	}
 
+#if __has_cpp_attribute(__gnu__::__pure__)
+	[[__gnu__::__pure__]]
+#endif
+	[[nodiscard]]
 	inline constexpr bool empty() const noexcept
 	{
 		return imp.begin_ptr == imp.curr_ptr;
 	}
 
+#if __has_cpp_attribute(__gnu__::__pure__)
+	[[__gnu__::__pure__]]
+#endif
+	[[nodiscard]]
 	inline constexpr size_type size() const noexcept
 	{
 		return static_cast<size_type>(imp.curr_ptr - imp.begin_ptr);
 	}
+
 	inline constexpr size_type size_bytes() const noexcept
 	{
 		return static_cast<size_type>(imp.curr_ptr - imp.begin_ptr) * sizeof(value_type);
@@ -524,7 +537,7 @@ class basic_string FAST_IO_TRIVIALLY_RELOCATABLE_IF_ELIGIBLE
 		this->assign_impl(other.imp.begin_ptr, static_cast<::std::size_t>(other.imp.curr_ptr - other.imp.begin_ptr));
 		return *this;
 	}
-	inline constexpr basic_string& operator=(string_view_type const &other) noexcept
+	inline constexpr basic_string &operator=(string_view_type const &other) noexcept
 	{
 		this->assign(other);
 		return *this;
diff --git a/include/fast_io_dsal/impl/string_view.h b/include/fast_io_dsal/impl/string_view.h
index ac377d3c..dd0dc8f7 100644
--- a/include/fast_io_dsal/impl/string_view.h
+++ b/include/fast_io_dsal/impl/string_view.h
@@ -66,16 +66,25 @@ class basic_string_view
 	const_pointer ptr{};
 	size_type n{};
 
+#if __has_cpp_attribute(__gnu__::__pure__)
+	[[__gnu__::__pure__]]
+#endif
 	[[nodiscard]] inline constexpr bool is_empty() const noexcept
 	{
 		return !n;
 	}
 
+#if __has_cpp_attribute(__gnu__::__pure__)
+	[[__gnu__::__pure__]]
+#endif
 	[[nodiscard]] inline constexpr bool empty() const noexcept
 	{
 		return !n;
 	}
 
+#if __has_cpp_attribute(__gnu__::__pure__)
+	[[__gnu__::__pure__]]
+#endif
 	[[nodiscard]] inline constexpr size_type size() const noexcept
 	{
 		return n;