diff --git a/libs/optional/test/optional.cpp b/libs/optional/test/optional.cpp
index 37f5b9e9..257e688d 100644
--- a/libs/optional/test/optional.cpp
+++ b/libs/optional/test/optional.cpp
@@ -434,18 +434,18 @@ namespace testspr {
 				TESTSPR_ASSERT(*sprout::get_pointer(opt3) == 12345);
 			}
 
-			// get_optional_value_or
-			TESTSPR_BOTH_ASSERT(sprout::get_optional_value_or(opt1, 12345) == 1234);
-			TESTSPR_BOTH_ASSERT(sprout::get_optional_value_or(opt2, 12345) == 12345);
+			// get_value_or
+			TESTSPR_BOTH_ASSERT(sprout::get_value_or(opt1, 12345) == 1234);
+			TESTSPR_BOTH_ASSERT(sprout::get_value_or(opt2, 12345) == 12345);
 			{
 				auto opt3 = sprout::optional<int>(1234);
 				int v = 12345;
-				TESTSPR_ASSERT(sprout::get_optional_value_or(opt3, v) == 1234);
+				TESTSPR_ASSERT(sprout::get_value_or(opt3, v) == 1234);
 			}
 			{
 				auto opt3 = sprout::optional<int>();
 				int v = 12345;
-				TESTSPR_ASSERT(sprout::get_optional_value_or(opt3, v) == 12345);
+				TESTSPR_ASSERT(sprout::get_value_or(opt3, v) == 12345);
 			}
 
 			// sprout::to_hash, sprout::hash
diff --git a/sprout/optional/get.hpp b/sprout/optional/get.hpp
index 8c2078b3..cd7334e3 100644
--- a/sprout/optional/get.hpp
+++ b/sprout/optional/get.hpp
@@ -9,52 +9,67 @@ namespace sprout {
 	// get
 	//
 	template<typename T>
-	inline SPROUT_CONSTEXPR typename sprout::optional<T>::reference_const_type
-	get(sprout::optional<T> const& x) {
-		return x.get();
+	inline SPROUT_CONSTEXPR typename sprout::optional<T>::reference_type
+	get(sprout::optional<T>& x) {
+		return sprout::optional<T>::get(x);
 	}
 	template<typename T>
-	inline typename sprout::optional<T>::reference_type
-	get(sprout::optional<T>& x) {
-		return x.get();
+	inline SPROUT_CONSTEXPR typename sprout::optional<T>::rvalue_reference_type
+	get(sprout::optional<T>&& x) {
+		return sprout::optional<T>::get(sprout::move(x));
+	}
+	template<typename T>
+	inline SPROUT_CONSTEXPR typename sprout::optional<T>::reference_const_type
+	get(sprout::optional<T> const& x) {
+		return sprout::optional<T>::get(x);
+	}
+	template<typename T>
+	inline SPROUT_CONSTEXPR typename sprout::optional<T>::pointer_type
+	get(sprout::optional<T>* x) {
+		return sprout::optional<T>::get_pointer(*x);
 	}
 	template<typename T>
 	inline SPROUT_CONSTEXPR typename sprout::optional<T>::pointer_const_type
 	get(sprout::optional<T> const* x) {
-		return x->get_pointer();
-	}
-	template<typename T>
-	inline typename sprout::optional<T>::pointer_type
-	get(sprout::optional<T>* x) {
-		return x->get_pointer();
+		return sprout::optional<T>::get_pointer(*x);
 	}
 
 	//
 	// get_pointer
 	//
 	template<typename T>
-	inline SPROUT_CONSTEXPR typename sprout::optional<T>::pointer_const_type
-	get_pointer(sprout::optional<T> const& x) {
-		return x.get_pointer();
+	inline SPROUT_CONSTEXPR typename sprout::optional<T>::pointer_type
+	get_pointer(sprout::optional<T>& x) {
+		return sprout::optional<T>::get_pointer(x);
 	}
 	template<typename T>
-	inline typename sprout::optional<T>::pointer_type
-	get_pointer(sprout::optional<T>& x) {
-		return x.get_pointer();
+	inline SPROUT_CONSTEXPR typename sprout::optional<T>::pointer_type
+	get_pointer(sprout::optional<T>&& x) {
+		return sprout::optional<T>::get_pointer(sprout::move(x));
+	}
+	template<typename T>
+	inline SPROUT_CONSTEXPR typename sprout::optional<T>::pointer_const_type
+	get_pointer(sprout::optional<T> const& x) {
+		return sprout::optional<T>::get_pointer(x);
 	}
 
 	//
-	// get_optional_value_or
+	// get_value_or
 	//
 	template<typename T>
-	inline SPROUT_CONSTEXPR typename sprout::optional<T>::reference_const_type
-	get_optional_value_or(sprout::optional<T> const& x, typename sprout::optional<T>::reference_const_type v) {
-		return x.get_value_or(v);
+	inline SPROUT_CONSTEXPR typename sprout::optional<T>::reference_type
+	get_value_or(sprout::optional<T>& x, typename sprout::optional<T>::reference_type v) {
+		return sprout::optional<T>::get_value_or(x, v);
 	}
 	template<typename T>
-	inline typename sprout::optional<T>::reference_type
-	get_optional_value_or(sprout::optional<T>& x, typename sprout::optional<T>::reference_type v) {
-		return x.get_value_or(v);
+	inline SPROUT_CONSTEXPR typename sprout::optional<T>::rvalue_reference_type
+	get_value_or(sprout::optional<T>&& x, typename sprout::optional<T>::rvalue_reference_type v) {
+		return sprout::optional<T>::get_value_or(sprout::move(x), static_cast<typename sprout::optional<T>::rvalue_reference_type>(v));
+	}
+	template<typename T>
+	inline SPROUT_CONSTEXPR typename sprout::optional<T>::reference_const_type
+	get_value_or(sprout::optional<T> const& x, typename sprout::optional<T>::reference_const_type v) {
+		return sprout::optional<T>::get_value_or(x, v);
 	}
 }	// namespace sprout
 
diff --git a/sprout/optional/optional.hpp b/sprout/optional/optional.hpp
index 93089a2d..f1d5f244 100644
--- a/sprout/optional/optional.hpp
+++ b/sprout/optional/optional.hpp
@@ -5,10 +5,10 @@
 #include <initializer_list>
 #include <sprout/config.hpp>
 #include <sprout/utility/value_holder/value_holder.hpp>
+#include <sprout/utility/value_holder/get.hpp>
 #include <sprout/utility/swap.hpp>
 #include <sprout/utility/forward.hpp>
 #include <sprout/utility/move.hpp>
-#include <sprout/utility/as_const.hpp>
 #include <sprout/type_traits/is_convert_constructible.hpp>
 #include <sprout/none.hpp>
 #include <sprout/optional/nullopt.hpp>
@@ -28,16 +28,52 @@ namespace sprout {
 		typedef sprout::value_holder<type> holder_type;
 	public:
 		typedef typename holder_type::value_type value_type;
+		typedef typename holder_type::lvalue_reference lvalue_reference;
+		typedef typename holder_type::rvalue_reference rvalue_reference;
 		typedef typename holder_type::reference reference;
+		typedef typename holder_type::const_lvalue_reference const_lvalue_reference;
+		typedef typename holder_type::const_rvalue_reference const_rvalue_reference;
 		typedef typename holder_type::const_reference const_reference;
 		typedef typename holder_type::pointer pointer;
 		typedef typename holder_type::const_pointer const_pointer;
+		typedef typename holder_type::lvalue_reference_type lvalue_reference_type;
+		typedef typename holder_type::rvalue_reference_type rvalue_reference_type;
 		typedef typename holder_type::reference_type reference_type;
 		typedef typename holder_type::reference_const_type reference_const_type;
 		typedef typename holder_type::pointer_type pointer_type;
 		typedef typename holder_type::pointer_const_type pointer_const_type;
-		typedef typename holder_type::argument_type argument_type;
-		typedef typename holder_type::movable_argument_type movable_argument_type;
+	public:
+		static SPROUT_CONSTEXPR reference_type get(optional& t) SPROUT_NOEXCEPT {
+			return sprout::get(t.val);
+		}
+		static SPROUT_CONSTEXPR rvalue_reference_type get(optional&& t) SPROUT_NOEXCEPT {
+			return static_cast<rvalue_reference_type>(get(t));
+		}
+		static SPROUT_CONSTEXPR reference_const_type get(optional const& t) SPROUT_NOEXCEPT {
+			return sprout::get(t.val);
+		}
+		static SPROUT_CONSTEXPR pointer_type get_pointer(optional& t) SPROUT_NOEXCEPT {
+			return sprout::get_pointer(t.val);
+		}
+		static SPROUT_CONSTEXPR pointer_type get_pointer(optional&& t) SPROUT_NOEXCEPT {
+			return get_pointer(t);
+		}
+		static SPROUT_CONSTEXPR pointer_const_type get_pointer(optional const& t) SPROUT_NOEXCEPT {
+			return sprout::get_pointer(t.val);
+		}
+		static SPROUT_CONSTEXPR reference_type get_value_or(optional& t, reference_type v) SPROUT_NOEXCEPT {
+			return t.is_initialized() ? sprout::get(t.val)
+				: v
+				;
+		}
+		static SPROUT_CONSTEXPR rvalue_reference_type get_value_or(optional&& t, rvalue_reference_type v) SPROUT_NOEXCEPT {
+			return static_cast<rvalue_reference_type>(get_value_or(t, v));
+		}
+		static SPROUT_CONSTEXPR reference_const_type get_value_or(optional const& t, reference_const_type v) SPROUT_NOEXCEPT {
+			return t.is_initialized() ? sprout::get(t.val)
+				: v
+				;
+		}
 	private:
 		bool init;
 		holder_type val;
@@ -57,16 +93,10 @@ namespace sprout {
 			: init(v.init)
 			, val(v.is_initialized() ? holder_type(*v) : holder_type())
 		{}
-		// constexpr support
-//		SPROUT_CONSTEXPR optional(optional&& v)
-//		SPROUT_NOEXCEPT_EXPR(std::is_nothrow_move_constructible<T>::value)
-//			: init(v.init)
-//			, val(v.is_initialized() ? holder_type(sprout::move(*v)) : holder_type())
-//		{}
 		SPROUT_CONSTEXPR optional(optional&& v)
-		SPROUT_NOEXCEPT_EXPR(std::is_nothrow_copy_constructible<T>::value)
+		SPROUT_NOEXCEPT_EXPR(std::is_nothrow_move_constructible<T>::value)
 			: init(v.init)
-			, val(v.is_initialized() ? holder_type(*sprout::as_const(v)) : holder_type())
+			, val(v.is_initialized() ? holder_type(sprout::move(get(v))) : holder_type())
 		{}
 		SPROUT_CONSTEXPR optional(T const& v)
 			: init(true)
@@ -105,16 +135,10 @@ namespace sprout {
 			: init(v.is_initialized())
 			, val(v.is_initialized() ? holder_type(*v) : holder_type())
 		{}
-		// constexpr support
-//		template<typename U>
-//		explicit SPROUT_CONSTEXPR optional(optional<U>&& v)
-//			: init(v.is_initialized())
-//			, val(v.is_initialized() ? holder_type(sprout::move(*v)) : holder_type())
-//		{}
 		template<typename U>
 		explicit SPROUT_CONSTEXPR optional(optional<U>&& v)
 			: init(v.is_initialized())
-			, val(v.is_initialized() ? holder_type(*sprout::as_const(v)) : holder_type())
+			, val(v.is_initialized() ? holder_type(sprout::move(optional<U>::get(v))) : holder_type())
 		{}
 		// 20.6.4.3, assignment
 		optional& operator=(sprout::nullopt_t v) SPROUT_NOEXCEPT {
diff --git a/sprout/tuple/tuple/get.hpp b/sprout/tuple/tuple/get.hpp
index 7b515061..b1871ac9 100644
--- a/sprout/tuple/tuple/get.hpp
+++ b/sprout/tuple/tuple/get.hpp
@@ -37,7 +37,7 @@ namespace sprout {
 		template<std::size_t I, typename... Types>
 		inline SPROUT_CONSTEXPR typename sprout::tuples::tuple_element<I, sprout::tuples::tuple<Types...> >::type&&
 		tuple_get(sprout::tuples::tuple<Types...>&& t) SPROUT_NOEXCEPT {
-			return sprout::forward<typename sprout::tuples::tuple_element<I, sprout::tuples::tuple<Types...> >::type&&>(
+			return sprout::forward<typename sprout::tuples::tuple_element<I, sprout::tuples::tuple<Types...> >::type>(
 				sprout::tuples::tuple_get<I>(t)
 				);
 		}
diff --git a/sprout/utility/value_holder/get.hpp b/sprout/utility/value_holder/get.hpp
index 648c4252..30de79df 100644
--- a/sprout/utility/value_holder/get.hpp
+++ b/sprout/utility/value_holder/get.hpp
@@ -3,44 +3,55 @@
 
 #include <sprout/config.hpp>
 #include <sprout/utility/value_holder/value_holder.hpp>
+#include <sprout/utility/move.hpp>
 
 namespace sprout {
 	//
 	// get
 	//
 	template<typename T>
-	inline SPROUT_CONSTEXPR typename sprout::value_holder<T>::reference_const_type
-	get(sprout::value_holder<T> const& x) {
-		return x.get();
+	inline SPROUT_CONSTEXPR typename sprout::value_holder<T>::reference_type
+	get(sprout::value_holder<T>& x) {
+		return sprout::value_holder<T>::get(x);
 	}
 	template<typename T>
-	inline typename sprout::value_holder<T>::reference_type
-	get(sprout::value_holder<T>& x) {
-		return x.get();
+	inline SPROUT_CONSTEXPR typename sprout::value_holder<T>::rvalue_reference
+	get(sprout::value_holder<T>&& x) {
+		return sprout::value_holder<T>::get(sprout::move(x));
+	}
+	template<typename T>
+	inline SPROUT_CONSTEXPR typename sprout::value_holder<T>::reference_const_type
+	get(sprout::value_holder<T> const& x) {
+		return sprout::value_holder<T>::get(x);
+	}
+	template<typename T>
+	inline SPROUT_CONSTEXPR typename sprout::value_holder<T>::pointer_type
+	get(sprout::value_holder<T>* x) {
+		return sprout::value_holder<T>::get_pointer(*x);
 	}
 	template<typename T>
 	inline SPROUT_CONSTEXPR typename sprout::value_holder<T>::pointer_const_type
 	get(sprout::value_holder<T> const* x) {
-		return x->get_pointer();
-	}
-	template<typename T>
-	inline typename sprout::value_holder<T>::pointer_type
-	get(sprout::value_holder<T>* x) {
-		return x->get_pointer();
+		return sprout::value_holder<T>::get_pointer(*x);
 	}
 
 	//
 	// get_pointer
 	//
 	template<typename T>
-	inline SPROUT_CONSTEXPR typename sprout::value_holder<T>::pointer_const_type
-	get_pointer(sprout::value_holder<T> const& x) {
-		return x.get_pointer();
+	inline SPROUT_CONSTEXPR typename sprout::value_holder<T>::pointer_type
+	get_pointer(sprout::value_holder<T>& x) {
+		return sprout::value_holder<T>::get_pointer(x);
 	}
 	template<typename T>
-	inline typename sprout::value_holder<T>::pointer_type
-	get_pointer(sprout::value_holder<T>& x) {
-		return x.get_pointer();
+	inline SPROUT_CONSTEXPR typename sprout::value_holder<T>::pointer_type
+	get_pointer(sprout::value_holder<T>&& x) {
+		return sprout::value_holder<T>::get_pointer(sprout::move(x));
+	}
+	template<typename T>
+	inline SPROUT_CONSTEXPR typename sprout::value_holder<T>::pointer_const_type
+	get_pointer(sprout::value_holder<T> const& x) {
+		return sprout::value_holder<T>::get_pointer(x);
 	}
 }	// namespace sprout
 
diff --git a/sprout/utility/value_holder/value_holder.hpp b/sprout/utility/value_holder/value_holder.hpp
index e5c6c23a..7f011009 100644
--- a/sprout/utility/value_holder/value_holder.hpp
+++ b/sprout/utility/value_holder/value_holder.hpp
@@ -15,8 +15,12 @@ namespace sprout {
 		struct holder_helper {
 		public:
 			typedef T value_type;
-			typedef T& reference;
-			typedef T const& const_reference;
+			typedef T& lvalue_reference;
+			typedef T&& rvalue_reference;
+			typedef lvalue_reference reference;
+			typedef T const& const_lvalue_reference;
+			typedef T const&& const_rvalue_reference;
+			typedef const_lvalue_reference const_reference;
 			typedef T const& mutable_or_const_reference;
 			typedef T* pointer;
 			typedef T const* const_pointer;
@@ -48,8 +52,12 @@ namespace sprout {
 		struct holder_helper<T const> {
 		public:
 			typedef T value_type;
-			typedef T const& reference;
-			typedef T const& const_reference;
+			typedef T const& lvalue_reference;
+			typedef T const&& rvalue_reference;
+			typedef lvalue_reference reference;
+			typedef T const& const_lvalue_reference;
+			typedef T const&& const_rvalue_reference;
+			typedef const_lvalue_reference const_reference;
 			typedef T const& mutable_or_const_reference;
 			typedef T const* pointer;
 			typedef T const* const_pointer;
@@ -81,8 +89,12 @@ namespace sprout {
 		struct holder_helper<T&> {
 		public:
 			typedef T value_type;
-			typedef T& reference;
-			typedef T const& const_reference;
+			typedef T& lvalue_reference;
+			typedef T& rvalue_reference;
+			typedef lvalue_reference reference;
+			typedef T const& const_lvalue_reference;
+			typedef T const& const_rvalue_reference;
+			typedef const_lvalue_reference const_reference;
 			typedef T& mutable_or_const_reference;
 			typedef T* pointer;
 			typedef T const* const_pointer;
@@ -105,8 +117,12 @@ namespace sprout {
 		struct holder_helper<T const&> {
 		public:
 			typedef T value_type;
-			typedef T const& reference;
-			typedef T const& const_reference;
+			typedef T const& lvalue_reference;
+			typedef T const& rvalue_reference;
+			typedef lvalue_reference reference;
+			typedef T const& const_lvalue_reference;
+			typedef T const& const_rvalue_reference;
+			typedef const_lvalue_reference const_reference;
 			typedef T const& mutable_or_const_reference;
 			typedef T const* pointer;
 			typedef T const* const_pointer;
@@ -138,7 +154,11 @@ namespace sprout {
 		typedef typename helper_type::holder_type holder_type;
 	public:
 		typedef typename helper_type::value_type value_type;
+		typedef typename helper_type::lvalue_reference lvalue_reference;
+		typedef typename helper_type::rvalue_reference rvalue_reference;
 		typedef typename helper_type::reference reference;
+		typedef typename helper_type::const_lvalue_reference const_lvalue_reference;
+		typedef typename helper_type::const_rvalue_reference const_rvalue_reference;
 		typedef typename helper_type::const_reference const_reference;
 		typedef typename helper_type::mutable_or_const_reference mutable_or_const_reference;
 		typedef typename helper_type::pointer pointer;
@@ -146,12 +166,33 @@ namespace sprout {
 		typedef typename helper_type::mutable_or_const_pointer mutable_or_const_pointer;
 		typedef typename helper_type::param_type param_type;
 		typedef typename helper_type::movable_param_type movable_param_type;
+		typedef lvalue_reference lvalue_reference_type;
+		typedef rvalue_reference rvalue_reference_type;
 		typedef reference reference_type;
 		typedef mutable_or_const_reference reference_const_type;
 		typedef pointer pointer_type;
 		typedef mutable_or_const_pointer pointer_const_type;
 		typedef param_type argument_type;
 		typedef movable_param_type movable_argument_type;
+	public:
+		static SPROUT_CONSTEXPR reference get(value_holder& t) SPROUT_NOEXCEPT {
+			return helper_type::ref(t.holder_);
+		}
+		static SPROUT_CONSTEXPR rvalue_reference get(value_holder&& t) SPROUT_NOEXCEPT {
+			return static_cast<rvalue_reference>(get(t));
+		}
+		static SPROUT_CONSTEXPR mutable_or_const_reference get(value_holder const& t) SPROUT_NOEXCEPT {
+			return helper_type::ref(t.holder_);
+		}
+		static SPROUT_CONSTEXPR pointer get_pointer(value_holder& t) SPROUT_NOEXCEPT {
+			return helper_type::ptr(t.holder_);
+		}
+		static SPROUT_CONSTEXPR pointer get_pointer(value_holder&& t) SPROUT_NOEXCEPT {
+			return get_pointer(t);
+		}
+		static SPROUT_CONSTEXPR mutable_or_const_pointer get_pointer(value_holder const& t) SPROUT_NOEXCEPT {
+			return helper_type::ptr(t.holder_);
+		}
 	private:
 		holder_type holder_;
 	public:
@@ -160,7 +201,7 @@ namespace sprout {
 		{}
 		SPROUT_CONSTEXPR value_holder(value_holder const&) = default;
 		SPROUT_CONSTEXPR value_holder(value_holder&&) = default;
-		explicit SPROUT_CONSTEXPR value_holder(param_type p)
+		explicit SPROUT_CONSTEXPR value_holder(argument_type p)
 			: holder_(helper_type::hold(p))
 		{}
 		explicit SPROUT_CONSTEXPR value_holder(movable_argument_type p)
@@ -183,7 +224,7 @@ namespace sprout {
 
 		value_holder& operator=(value_holder const&) = default;
 		value_holder& operator=(value_holder&&) = default;
-		value_holder& operator=(param_type p) {
+		value_holder& operator=(argument_type p) {
 			value_holder temp(helper_type::hold(p));
 			temp.swap(p);
 			return *this;
@@ -218,6 +259,12 @@ namespace sprout {
 		SPROUT_CONSTEXPR mutable_or_const_reference get() const {
 			return helper_type::ref(holder_);
 		}
+		reference value() {
+			return get();
+		}
+		SPROUT_CONSTEXPR mutable_or_const_reference value() const {
+			return get();
+		}
 
 		pointer operator->() SPROUT_NOEXCEPT {
 			return helper_type::ptr(holder_);