diff --git a/src/cpputils/container/smart_ptr.h b/src/cpputils/container/smart_ptr.h
index 69fcdb4..26692a7 100644
--- a/src/cpputils/container/smart_ptr.h
+++ b/src/cpputils/container/smart_ptr.h
@@ -16,19 +16,19 @@ namespace utl
 
         template<class X, class Enable = void>
         struct __impl_cop_is_value :
-            public mp::c_true { };
+            public mp::c_true;
 
         template<class X>
         struct __impl_cop_is_value<X*, void> :
-            public mp::c_false { };
+            public mp::c_false;
 
         template<template<class> class F, class X>
         struct __impl_cop_is_value<F<X>, mp::enable_if<cop_is_base_of<smart_ptr<X>, F<X>>>> :
-            public mp::c_false { };
+            public mp::c_false;
 
         template<class X>
         struct __impl_cop_is_value<std::reference_wrapper<X>, void> :
-            public mp::c_false { };
+            public mp::c_false;
 
         template<class X>
         using cop_is_value = __impl_cop_is_value<mp::clean_type<X>>;
diff --git a/src/cpputils/mp.h b/src/cpputils/mp.h
index 2a5525e..1016fc8 100644
--- a/src/cpputils/mp.h
+++ b/src/cpputils/mp.h
@@ -1,7 +1,7 @@
 #pragma once
 
 #include <cpputils/mp/core.h>
-#include <cpputils/mp/util.h>
+#include <cpputils/mp/misc.h>
 #include <cpputils/mp/intern.h>
 #include <cpputils/mp/container.h>
 #include <cpputils/mp/operations.h>
\ No newline at end of file
diff --git a/src/cpputils/mp/container.h b/src/cpputils/mp/container.h
index ce813a9..9af1b05 100644
--- a/src/cpputils/mp/container.h
+++ b/src/cpputils/mp/container.h
@@ -1,3 +1,6 @@
 #pragma once
 
-#include <cpputils/mp/container/pair.h>
\ No newline at end of file
+#include <cpputils/mp/container/basic_tuple.h>
+#include <cpputils/mp/container/map.h>
+#include <cpputils/mp/container/pair.h>
+#include <cpputils/mp/container/type.h>
diff --git a/src/cpputils/mp/container/basic_tuple.h b/src/cpputils/mp/container/basic_tuple.h
new file mode 100644
index 0000000..8e2d1d1
--- /dev/null
+++ b/src/cpputils/mp/container/basic_tuple.h
@@ -0,0 +1,159 @@
+#pragma once
+
+#include <utility>
+#include <cpputils/mp/core/modifier.h>
+#include <cpputils/mp/core/conditionals.h>
+#include <cpputils/mp/misc/make.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/intern/ebo.h>
+#include <cpputils/mp/operations/at.h>
+#include <cpputils/mp/operations/unpack.h>
+#include <cpputils/mp/operations/transform.h>
+
+namespace utl {
+namespace mp {
+
+    struct tag_basic_tuple { };
+
+    namespace __impl 
+    {
+        template<size_t>
+        struct basic_tuple_index;
+
+        template<typename Indices, typename... Xn>
+        struct basic_tuple_impl;
+
+        struct basic_tuple_from_other { };
+
+        template<size_t... N, typename... Xn>
+        struct basic_tuple_impl<std::index_sequence<N...>, Xn...>
+            : intern::ebo<basic_tuple_index<N>, Xn>...
+        {
+            static constexpr size_t _size = sizeof...(Xn);
+
+            constexpr basic_tuple_impl() = default;
+
+            template<typename Other>
+            explicit constexpr basic_tuple_impl(basic_tuple_from_other, Other&& other)
+                : intern::ebo<basic_tuple_index<N>, Xn>(intern::ebo_get<basic_tuple_index<N>>(std::forward<Other>(other)))...
+                { }
+
+            template<typename... Yn>
+            explicit constexpr basic_tuple_impl(Yn&&... yn) 
+                : intern::ebo<basic_tuple_index<N>, Xn>(std::forward<Yn>(yn))...
+                { }
+        };
+    }
+
+    template<typename... Xn>
+    struct basic_tuple final
+        : __impl::basic_tuple_impl<std::make_index_sequence<sizeof...(Xn)>, Xn...>
+    {
+        using tag       = tag_basic_tuple;
+        using base_type = __impl::basic_tuple_impl<std::make_index_sequence<sizeof...(Xn)>, Xn...>;
+
+        constexpr basic_tuple() = default;
+
+        template<typename Other, typename = enable_if<is_same<basic_tuple, decay_type<Other>>>>
+        constexpr basic_tuple(Other&& other)
+            : base_type(__impl::basic_tuple_from_other { }, std::forward<Other>(other))
+            { }
+
+        template<typename... Yn>
+        explicit constexpr basic_tuple(Yn&&... yn)
+            : base_type(std::forward<Yn>(yn)...)
+            { }
+
+        template<typename N>
+        constexpr auto at(const N& n) const
+            { return mp::at(*this, n); }
+
+        template<typename F>
+        constexpr auto unpack(F&& f) const
+            { return mp::unpack(*this, std::forward<F>(f)); }
+        
+        template<typename F>
+        constexpr auto transform(F&& f) const
+            { return mp::transform(*this, std::forward<F>(f)); }
+    };
+
+    constexpr auto make_basic_tuple = make<tag_basic_tuple>;
+
+    namespace __impl
+    {
+        /* tag_of */
+        template<typename... Xn>
+        struct tag_of_impl<basic_tuple<Xn...>>
+            { using type = tag_basic_tuple; };
+
+        /* make */
+        template<>
+        struct make_impl<tag_basic_tuple>
+        {
+            template<typename... Xn>
+            static constexpr auto apply(Xn&&... xn)
+                { return basic_tuple<decay_type<Xn>...> { std::forward<Xn>(xn)... }; }
+        };
+
+        /* unpack */
+        template<>
+        struct unpack_impl<tag_basic_tuple>
+        {
+            template<size_t... I, typename... Xn, typename F>
+            static constexpr auto apply(const basic_tuple_impl<std::index_sequence<I...>, Xn...>& xs, F&& f)
+            {
+                return std::forward<F>(f)(
+                    intern::ebo_get<basic_tuple_index<I>>(
+                        static_cast<const intern::ebo<basic_tuple_index<I>, Xn>&>(xs)
+                    )...
+                );
+            }
+
+            template<size_t... I, typename... Xn, typename F>
+            static constexpr auto apply(basic_tuple_impl<std::index_sequence<I...>, Xn...>& xs, F&& f)
+            {
+                return std::forward<F>(f)(
+                    intern::ebo_get<basic_tuple_index<I>>(
+                        static_cast<intern::ebo<basic_tuple_index<I>, Xn>&>(xs)
+                    )...
+                );
+            }
+
+            template<size_t... I, typename... Xn, typename F>
+            static constexpr auto apply(basic_tuple_impl<std::index_sequence<I...>, Xn...>&& xs, F&& f)
+            {
+                return std::forward<F>(f)(
+                    intern::ebo_get<basic_tuple_index<I>>(
+                        static_cast<intern::ebo<basic_tuple_index<I>, Xn>&&>(xs)
+                    )...
+                );
+            }
+        };
+
+        /* at */
+        template<>
+        struct at_impl<tag_basic_tuple>
+        {
+            template<typename Xs, typename N>
+            static constexpr auto apply(Xs&& xs, const N&)
+            {
+                constexpr size_t index = N::value;
+                return intern::ebo_get<basic_tuple_index<index>>(std::forward<Xs>(xs));
+            }
+        };
+    }
+
+    template <size_t N, typename... Xn>
+    constexpr auto at_c(const basic_tuple<Xn...>& x)
+        { return intern::ebo_get<__impl::basic_tuple_index<N>>(x); }
+
+    template <size_t N, typename... Xn>
+    constexpr auto at_c(basic_tuple<Xn...>& x)
+        { return intern::ebo_get<__impl::basic_tuple_index<N>>(x); }
+
+    template <size_t N, typename... Xn>
+    constexpr auto at_c(basic_tuple<Xn...>&& x)
+        { return intern::ebo_get<__impl::basic_tuple_index<N>>(std::forward<basic_tuple<Xn...>>(x)); }
+
+}
+}
\ No newline at end of file
diff --git a/src/cpputils/mp/container/map.h b/src/cpputils/mp/container/map.h
new file mode 100644
index 0000000..4705b94
--- /dev/null
+++ b/src/cpputils/mp/container/map.h
@@ -0,0 +1,36 @@
+#pragma once
+
+#include <cpputils/mp/misc/to.h>
+#include <cpputils/mp/misc/make.h>
+#include <cpputils/mp/container/basic_tuple.h>
+
+namespace utl {
+namespace mp {
+
+    struct tag_map { };
+
+    constexpr auto make_map = make<tag_map>;
+
+    constexpr auto to_map = make<tag_map>;
+
+    namespace __impl /* forward declaration */
+    {
+        template<typename... Pairs>
+        struct make_map_type;
+    }
+
+    template<typename... Pairs>
+    using map = typename __impl::make_map_type<Pairs...>::type;
+
+    namespace __impl /* implementation */
+    {
+        template<typename... Pairs>
+        struct make_map_type
+        {
+            using storage_type = basic_tuple<Pairs...>;
+            
+        };
+    }
+
+}
+}
\ No newline at end of file
diff --git a/src/cpputils/mp/container/pair.h b/src/cpputils/mp/container/pair.h
index 632bf98..8d5353d 100644
--- a/src/cpputils/mp/container/pair.h
+++ b/src/cpputils/mp/container/pair.h
@@ -1,8 +1,8 @@
 #pragma once
 
 #include <cpputils/mp/core.h>
-#include <cpputils/mp/util/make.h>
-#include <cpputils/mp/util/tag_of.h>
+#include <cpputils/mp/misc/make.h>
+#include <cpputils/mp/misc/tag_of.h>
 #include <cpputils/mp/intern/ebo.h>
 #include <cpputils/mp/intern/operators_orderable.h>
 #include <cpputils/mp/intern/operators_comparable.h>
@@ -33,6 +33,7 @@ namespace mp {
         private intern::ebo<__impl::pair_index<0>, First>,
         private intern::ebo<__impl::pair_index<1>, Second>
     {
+        using tag       = tag_pair;
         using this_type = pair<First, Second>;
 
         // default constructor
diff --git a/src/cpputils/mp/container/type.h b/src/cpputils/mp/container/type.h
new file mode 100644
index 0000000..c8e2451
--- /dev/null
+++ b/src/cpputils/mp/container/type.h
@@ -0,0 +1,268 @@
+#pragma once
+
+#include <utility>
+#include <cpputils/mp/misc/make.h>
+#include <cpputils/mp/core/const.h>
+#include <cpputils/mp/core/modifier.h>
+#include <cpputils/mp/operations/hash.fwd.h>
+#include <cpputils/mp/intern/operators_comparable.h>
+
+namespace utl {
+namespace mp {
+
+    namespace __impl /* forward declaration */
+    {
+        template<typename T>
+        struct type_impl;
+
+        struct decl_type_t
+        {
+            template<typename T>
+            constexpr auto operator()(T&& t) const;
+        };
+
+        struct type_id_t
+        {
+            template <typename T>
+            constexpr auto operator()(T&&) const;
+        };
+
+        struct size_of_t
+        {
+            template <typename T>
+            constexpr auto operator()(T&&) const;
+        };
+
+        struct align_of_t
+        {
+            template <typename T>
+            constexpr auto operator()(T&&) const;
+        };
+
+        struct is_valid_type_t
+        {
+            template <typename F>
+            constexpr auto operator()(F&&) const;
+
+            template <typename F, typename ...Args>
+            constexpr auto operator()(F&&, Args&&...) const;
+        };
+
+        template <template <typename ...> class F>
+        struct tmplt_t;
+
+        template <template <typename ...> class F>
+        struct metafunction_t;
+
+        template <typename F>
+        struct metafunction_class_t
+            : metafunction_t<F::template apply>
+            { };
+
+        template <typename F>
+        struct integral_t;
+
+        struct make_integral_t
+        {
+            template <typename F>
+            constexpr integral_t<F> operator()(F const&) const
+                { return { }; }
+        };
+    }
+
+    struct tag_type { };
+
+    template<typename T>
+    using type = typename __impl::type_impl<T>::type;
+
+    template<typename T>
+    constexpr type<T> type_c { };
+
+    constexpr auto make_mp_type = make<tag_type>;
+
+    constexpr __impl::decl_type_t decl_type { };
+
+    constexpr __impl::type_id_t type_id { };
+
+    constexpr __impl::size_of_t size_of { };
+
+    constexpr __impl::align_of_t align_of { };
+
+    constexpr __impl::is_valid_type_t is_valid_type { };
+
+    template <template <typename ...> class F>
+    constexpr __impl::tmplt_t<F> tmplt { };
+
+    template <template <typename ...> class F>
+    constexpr __impl::metafunction_t<F> metafunction { };
+
+    template <typename F>
+    constexpr __impl::metafunction_class_t<F> metafunction_class { };
+
+    constexpr __impl::make_integral_t integral { };
+
+    template <template <typename ...> class F>
+    constexpr auto trait = integral(metafunction<F>);
+
+    namespace __impl /* implementation */
+    {
+        /* basic_type */
+        template<typename T>
+        struct basic_type
+        {
+            using tag  = tag_type;
+            using type = T;
+
+            constexpr auto operator+() const
+                { return *this; }
+        };
+
+        /* type */
+        template<typename T>
+        struct type_impl
+        { 
+            struct type : basic_type<T> 
+                { };
+        };
+
+        /* decl_type */
+        template <typename T, typename = tag_type>
+        struct decltype_helper
+            { using type = remove_ref<T>; };
+
+        template <typename T>
+        struct decltype_helper<T, tag_of<T>>
+            { using type = typename remove_ref<T>::type; };
+
+        template<typename T>
+        constexpr auto decl_type_t::operator()(T&& t) const
+            { return type_c<typename decltype_helper<T>::type>; }
+        
+        /* type_id */
+        template <typename T, typename = tag_type>
+        struct typeid_helper
+            { using type = clean_type<T>; };
+
+        template <typename T>
+        struct typeid_helper<T, tag_of<T>>
+            { using type = typename remove_ref<T>::type; };
+
+        template <typename T>
+        constexpr auto type_id_t::operator()(T&&) const
+            { return type_c<typename typeid_helper<T>::type>; }
+
+        /* make */
+        template <>
+        struct make_impl<tag_type>
+        {
+            template <typename T>
+            static constexpr auto apply(T&& t)
+                { return type_id(std::forward<T>(t)); }
+        };
+
+        /* size_of */
+        template <typename T>
+        constexpr auto size_of_t::operator()(T&&) const
+            { return c_size_t<sizeof(typename decltype_helper<T>::type)> { }; }
+        
+        /* align_of */
+        template <typename T>
+        constexpr auto align_of_t::operator()(T&&) const
+            { return c_size_t<alignof(typename decltype_helper<T>::type)> { }; }
+        
+        /* is_valid_type */
+        template<typename F, typename... Args, typename = decltype(std::declval<F&&>()(std::declval<Args&&>()...))>
+        constexpr auto is_valid_type_impl(int)
+            { return c_true; }
+
+        template<typename F, typename... Args>
+        constexpr auto is_valid_type_impl(...)
+            { return c_false; }
+
+        template<typename F>
+        struct is_valid_type_helper
+        {
+            template<typename... Args>
+            constexpr auto operator()(Args&&...) const
+                { return is_valid_type_impl<F, Args&&...>(int { }); }
+        };
+
+        template <typename F>
+        constexpr auto is_valid_type_t::operator()(F&&) const
+            { return is_valid_type_helper<F&&> { }; }
+
+        template <typename F, typename ...Args>
+        constexpr auto is_valid_type_t::operator()(F&&, Args&&...) const
+            { return is_valid_type_impl<F&&, Args&&...>(int { }); }
+
+        /* tmplt */
+        template <template <typename ...> class F>
+        struct tmplt_t
+        {
+            template<typename... T>
+            struct apply
+                { using type = F<T...>; };
+            
+            template<typename... T>
+            constexpr auto operator()(const T&...) const
+                { return type<F<typename T::type...>> { }; }
+        };
+
+        /* metafunction */
+        template <template <typename ...> class F>
+        struct metafunction_t
+        {
+            template<typename... T>
+            using apply = F<T...>;
+
+            template<typename... T>
+            constexpr type<typename F<typename T::type...>::type> operator()(const T&...) const
+                { return { }; }
+        };
+
+        /* integral */
+        template <typename F>
+        struct integral_t
+        {
+            template<typename... T>
+            constexpr auto operator()(const T& ...) const
+            {
+                using result_type = typename F::template apply<typename T::type...>::type;
+                return result_type { };
+            }
+        };
+
+        /* equal */
+        template <>
+        struct equal_impl<tag_type, tag_type>
+        {
+            template <typename T, typename U>
+            static constexpr auto apply(const basic_type<T>&, const basic_type<U>&)
+                { return c_false; }
+
+            template <typename T>
+            static constexpr auto apply(const basic_type<T>&, const basic_type<T>&)
+                { return c_true; }
+        };
+
+        /* hash */
+        template<>
+        struct hash_impl<tag_type>
+        {
+            template <typename T>
+            static constexpr T apply(const T& t)
+                { return t; }
+        };
+
+    }
+
+    namespace intern {
+
+        template<>
+        struct operators_comparable<tag_type>
+            { static constexpr bool value = true; };
+
+    }
+
+}
+}
\ No newline at end of file
diff --git a/src/cpputils/mp/core/checker.h b/src/cpputils/mp/core/checker.h
index 77907cd..24b587b 100644
--- a/src/cpputils/mp/core/checker.h
+++ b/src/cpputils/mp/core/checker.h
@@ -13,37 +13,43 @@ namespace mp {
     }
 
     template<typename T, typename S>
-    using is_same = c_bool<std::is_same<T, S>::value>;
+    using is_same = c_bool_t<std::is_same<T, S>::value>;
 
     template<typename Base, typename Derived>
-    using is_base_of = c_bool<std::is_base_of<Base, Derived>::value>;
+    using is_base_of = c_bool_t<std::is_base_of<Base, Derived>::value>;
 
     template<typename... T>
-    using is_constructible = c_bool<std::is_constructible<T...>::value>;
+    using is_constructible = c_bool_t<std::is_constructible<T...>::value>;
 
     template<typename... T>
-    using is_empty = c_bool<std::is_empty<T...>::value>;
+    using is_empty = c_bool_t<std::is_empty<T...>::value>;
 
     template<typename... T>
-    using is_final = c_bool<std::is_final<T...>::value>;
+    using is_final = c_bool_t<std::is_final<T...>::value>;
 
     template<typename T, typename U>
-    using is_convertible = c_bool<std::is_convertible<T, U>::value>;
+    using is_convertible = c_bool_t<std::is_convertible<T, U>::value>;
 
     template<typename T, typename U>
-    using is_assignable = c_bool<std::is_assignable<T, U>::value>;
+    using is_assignable = c_bool_t<std::is_assignable<T, U>::value>;
 
     template<typename... T>
     using is_valid = __impl::is_valid_impl<T...>;
 
     template<typename T>
-    using is_arithmetic = c_bool<std::is_arithmetic<T>::value>;
+    using is_arithmetic = c_bool_t<std::is_arithmetic<T>::value>;
+
+    template<typename T>
+    using is_signed = c_bool_t<std::is_signed<T>::value>;
+
+    template<typename T>
+    using is_unsigned = c_bool_t<std::is_unsigned<T>::value>;
 
     namespace __impl /* implementation */
     {
         template<typename...>
         struct is_valid_impl :
-            public c_true
+            public c_true_t
             { };
     }
 
diff --git a/src/cpputils/mp/core/const.h b/src/cpputils/mp/core/const.h
index 5f9c404..cbd3586 100644
--- a/src/cpputils/mp/core/const.h
+++ b/src/cpputils/mp/core/const.h
@@ -7,24 +7,31 @@ namespace utl {
 namespace mp {
 
     template<typename T>
-    struct tag_const { };
+    struct tag_integral_constant { };
 
     template<typename T, T t>
     struct integral_constant :
         public std::integral_constant<T, t>
     {
-        using tag = tag_const<T>;
+        using tag = tag_integral_constant<T>;
     };
 
     template<bool B>
-    using c_bool = integral_constant<bool, B>;
+    using c_bool_t = integral_constant<bool, B>;
 
     template<size_t S>
     using c_size_t = integral_constant<size_t, S>;
 
-    using c_true  = c_bool<true>;
-    using c_false = c_bool<false>;
-    using c_zero  = c_size_t<0>;
+    using c_zero_t  = c_size_t<0>;
+    using c_true_t  = c_bool_t<true>;
+    using c_false_t = c_bool_t<false>;
+
+    template<size_t S>
+    constexpr c_size_t<S> c_size { };
+
+    constexpr c_zero_t  c_zero { };
+    constexpr c_true_t  c_true { };
+    constexpr c_false_t c_false { };
 
 }
 }
\ No newline at end of file
diff --git a/src/cpputils/mp/intern.h b/src/cpputils/mp/intern.h
index 5f6f0e7..4f05770 100644
--- a/src/cpputils/mp/intern.h
+++ b/src/cpputils/mp/intern.h
@@ -1,3 +1,11 @@
 #pragma once
 
-#include <cpputils/mp/intern/ebo.h>
\ No newline at end of file
+#include <cpputils/mp/intern/comparable_equal.h>
+#include <cpputils/mp/intern/comparable_less.h>
+#include <cpputils/mp/intern/ebo.h>
+#include <cpputils/mp/intern/fold_left.h>
+#include <cpputils/mp/intern/fold_right.h>
+#include <cpputils/mp/intern/has_value.h>
+#include <cpputils/mp/intern/hash_table.h>
+#include <cpputils/mp/intern/operators_comparable.h>
+#include <cpputils/mp/intern/operators_orderable.h>
\ No newline at end of file
diff --git a/src/cpputils/mp/intern/comparable_equal.h b/src/cpputils/mp/intern/comparable_equal.h
index a51ab12..797e839 100644
--- a/src/cpputils/mp/intern/comparable_equal.h
+++ b/src/cpputils/mp/intern/comparable_equal.h
@@ -9,14 +9,14 @@ namespace intern {
 
     template<typename T, typename U = T, typename = void>
     struct comparable_equal
-        : c_false
+        : c_false_t
         { };
 
     template<typename T>
     struct comparable_equal<T, T, void_t<
         decltype(std::forward<T>(std::declval<T>()) == std::forward<T>(std::declval<T>()) ? 0 : 0),
         decltype(std::forward<T>(std::declval<T>()) != std::forward<T>(std::declval<T>()) ? 0 : 0)>>
-        : c_true
+        : c_true_t
         { };
 
     template <typename T, typename U>
@@ -28,7 +28,7 @@ namespace intern {
             decltype(std::forward<T>(std::declval<T>()) != std::forward<U>(std::declval<U>()) ? 0 : 0),
             decltype(std::forward<U>(std::declval<U>()) != std::forward<T>(std::declval<T>()) ? 0 : 0),
             common_type<T, U>>>>
-        : c_bool<
+        : c_bool_t<
             comparable_equal<T>::value &&
             comparable_equal<U>::value &&
             comparable_equal<common_type<T, U>>::value>
diff --git a/src/cpputils/mp/intern/comparable_less.h b/src/cpputils/mp/intern/comparable_less.h
index c012b93..17823e7 100644
--- a/src/cpputils/mp/intern/comparable_less.h
+++ b/src/cpputils/mp/intern/comparable_less.h
@@ -9,13 +9,13 @@ namespace intern {
 
     template<typename T, typename U = T, typename = void>
     struct comparable_less
-        : c_false
+        : c_false_t
         { };
 
     template<typename T>
     struct comparable_less<T, T, void_t<
         decltype(std::forward<T>(std::declval<T>()) < std::forward<T>(std::declval<T>()) ? 0 : 0)>>
-        : c_true
+        : c_true_t
         { };
 
     template <typename T, typename U>
@@ -25,7 +25,7 @@ namespace intern {
             decltype(std::forward<T>(std::declval<T>()) < std::forward<U>(std::declval<U>()) ? 0 : 0),
             decltype(std::forward<U>(std::declval<U>()) < std::forward<T>(std::declval<T>()) ? 0 : 0),
             common_type<T, U>>>>
-        : c_bool<
+        : c_bool_t<
             comparable_less<T>::value &&
             comparable_less<U>::value &&
             comparable_less<common_type<T, U>>::value>
diff --git a/src/cpputils/mp/intern/fold_left.h b/src/cpputils/mp/intern/fold_left.h
new file mode 100644
index 0000000..f0a3d8f
--- /dev/null
+++ b/src/cpputils/mp/intern/fold_left.h
@@ -0,0 +1,265 @@
+#pragma once
+
+#include <utility>
+#include <cpputils/mp/misc/when.h>
+
+namespace utl {
+namespace mp {
+namespace intern {
+
+    namespace __impl
+    {
+        template <unsigned int n, typename = when<true>>
+        struct fold_left_impl;
+
+        template<>
+        struct fold_left_impl<1>
+        {
+            template<typename F, typename X1>
+            static constexpr X1 apply(F&&, X1&& x1)
+                { return std::forward<X1>(x1); }
+        };
+
+        template<>
+        struct fold_left_impl<2>
+        {
+            template<typename F, typename X1, typename X2>
+            static constexpr auto apply(F&& f, X1&& x1, X2&& x2)
+            {
+                return f(
+                    std::forward<X1>(x1),
+                    std::forward<X2>(x2));
+            }
+        };
+
+        template<>
+        struct fold_left_impl<3>
+        {
+            template<typename F, typename X1, typename X2, typename X3>
+            static constexpr auto apply(F&& f, X1&& x1, X2&& x2, X3&& x3)
+            {
+                return f(f(
+                    std::forward<X1>(x1),
+                    std::forward<X2>(x2)),
+                    std::forward<X3>(x3));
+            }
+        };
+
+        template<>
+        struct fold_left_impl<4>
+        {
+            template<typename F, typename X1, typename X2, typename X3, typename X4>
+            static constexpr auto apply(F&& f, X1&& x1, X2&& x2, X3&& x3, X4&& x4)
+            {
+                return f(f(f(
+                    std::forward<X1>(x1),
+                    std::forward<X2>(x2)),
+                    std::forward<X3>(x3)),
+                    std::forward<X4>(x4));
+            }
+        };
+
+        template<>
+        struct fold_left_impl<5>
+        {
+            template<typename F, typename X1, typename X2, typename X3, typename X4, typename X5>
+            static constexpr auto apply(F&& f, X1&& x1, X2&& x2, X3&& x3, X4&& x4, X5&& x5)
+            {
+                return f(f(f(f(
+                    std::forward<X1>(x1),
+                    std::forward<X2>(x2)),
+                    std::forward<X3>(x3)),
+                    std::forward<X4>(x4)),
+                    std::forward<X5>(x5));
+            }
+        };
+
+        template<>
+        struct fold_left_impl<6>
+        {
+            template<typename F, typename X1, typename X2, typename X3, typename X4, typename X5, typename X6>
+            static constexpr auto apply(F&& f, X1&& x1, X2&& x2, X3&& x3, X4&& x4, X5&& x5, X6&& x6)
+            {
+                return f(f(f(f(f(
+                    std::forward<X1>(x1),
+                    std::forward<X2>(x2)),
+                    std::forward<X3>(x3)),
+                    std::forward<X4>(x4)),
+                    std::forward<X5>(x5)),
+                    std::forward<X6>(x6));
+            }
+        };
+
+        template<>
+        struct fold_left_impl<7>
+        {
+            template<typename F, typename X1, typename X2, typename X3, typename X4, typename X5, typename X6, typename X7>
+            static constexpr auto apply(F&& f, X1&& x1, X2&& x2, X3&& x3, X4&& x4, X5&& x5, X6&& x6, X7&& x7)
+            {
+                return f(f(f(f(f(f(
+                    std::forward<X1>(x1),
+                    std::forward<X2>(x2)),
+                    std::forward<X3>(x3)),
+                    std::forward<X4>(x4)),
+                    std::forward<X5>(x5)),
+                    std::forward<X6>(x6)),
+                    std::forward<X7>(x7));
+            }
+        };
+
+        template<>
+        struct fold_left_impl<8>
+        {
+            template<typename F, typename X1, typename X2, typename X3, typename X4, typename X5, typename X6, typename X7, typename X8>
+            static constexpr auto apply(F&& f, X1&& x1, X2&& x2, X3&& x3, X4&& x4, X5&& x5, X6&& x6, X7&& x7, X8&& x8)
+            {
+                return f(f(f(f(f(f(f(
+                    std::forward<X1>(x1),
+                    std::forward<X2>(x2)),
+                    std::forward<X3>(x3)),
+                    std::forward<X4>(x4)),
+                    std::forward<X5>(x5)),
+                    std::forward<X6>(x6)),
+                    std::forward<X7>(x7)),
+                    std::forward<X8>(x8));
+            }
+        };
+
+        template<unsigned int n>
+        struct fold_left_impl<n, when<(n >= 9) && (n < 18)>>
+        {
+            template<typename F, typename X1, typename X2, typename X3, typename X4, typename X5, typename X6, typename X7, typename X8, typename X9, typename... Xn>
+            static constexpr auto apply(F&& f, X1&& x1, X2&& x2, X3&& x3, X4&& x4, X5&& x5, X6&& x6, X7&& x7, X8&& x8, X9&& x9, Xn&&... xn)
+            {
+                return fold_left_impl<sizeof...(xn) + 1>::apply(
+                    f,
+                    f(f(f(f(f(f(f(f(
+                        std::forward<X1>(x1),
+                        std::forward<X2>(x2)),
+                        std::forward<X3>(x3)),
+                        std::forward<X4>(x4)),
+                        std::forward<X5>(x5)),
+                        std::forward<X6>(x6)),
+                        std::forward<X7>(x7)),
+                        std::forward<X8>(x8)),
+                        std::forward<X9>(x9)),
+                    std::forward<Xn>(xn)...
+                );
+            }
+        };
+
+        template<unsigned int n>
+        struct fold_left_impl<n, when<(n >= 18) && (n < 36)>>
+        {
+            template<
+                typename F,
+                typename X1,  typename X2,  typename X3,  typename X4,  typename X5,  typename X6,  typename X7,  typename X8,  typename X9,
+                typename X10, typename X11, typename X12, typename X13, typename X14, typename X15, typename X16, typename X17, typename X18,
+                typename... Xn>
+            static constexpr auto apply(
+                F&& f,
+                X1&&  x1,  X2&&  x2,  X3&&  x3,  X4&&  x4,  X5&&  x5,  X6&&  x6,  X7&&  x7,  X8&&  x8,  X9&&  x9,
+                X10&& x10, X11&& x11, X12&& x12, X13&& x13, X14&& x14, X15&& x15, X16&& x16, X17&& x17, X18&& x18,
+                Xn&&... xn)
+            {
+                return fold_left_impl<sizeof...(xn) + 1>::apply(
+                    f,
+                    f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(
+                        std::forward<X1> (x1),
+                        std::forward<X2> (x2)),
+                        std::forward<X3> (x3)),
+                        std::forward<X4> (x4)),
+                        std::forward<X5> (x5)),
+                        std::forward<X6> (x6)),
+                        std::forward<X7> (x7)),
+                        std::forward<X8> (x8)),
+                        std::forward<X9> (x9)),
+                        std::forward<X10>(x10)),
+                        std::forward<X11>(x11)),
+                        std::forward<X12>(x12)),
+                        std::forward<X13>(x13)),
+                        std::forward<X14>(x14)),
+                        std::forward<X15>(x15)),
+                        std::forward<X16>(x16)),
+                        std::forward<X17>(x17)),
+                        std::forward<X18>(x18)),
+                    std::forward<Xn>(xn)...
+                );
+            }
+        };
+
+        template<unsigned int n>
+        struct fold_left_impl<n, when<(n >= 36)>>
+        {
+            template<
+                typename F,
+                typename X1,  typename X2,  typename X3,  typename X4,  typename X5,  typename X6,  typename X7,  typename X8,  typename X9,
+                typename X10, typename X11, typename X12, typename X13, typename X14, typename X15, typename X16, typename X17, typename X18,
+                typename X19, typename X20, typename X21, typename X22, typename X23, typename X24, typename X25, typename X26, typename X27,
+                typename X28, typename X29, typename X30, typename X31, typename X32, typename X33, typename X34, typename X35, typename X36,
+                typename... Xn>
+            static constexpr auto apply(
+                F&& f,
+                X1&&  x1,  X2&&  x2,  X3&&  x3,  X4&&  x4,  X5&&  x5,  X6&&  x6,  X7&&  x7,  X8&&  x8,  X9&&  x9,
+                X10&& x10, X11&& x11, X12&& x12, X13&& x13, X14&& x14, X15&& x15, X16&& x16, X17&& x17, X18&& x18,
+                X19&& x19, X20&& x20, X21&& x21, X22&& x22, X23&& x23, X24&& x24, X25&& x25, X26&& x26, X27&& x27,
+                X28&& x28, X29&& x29, X30&& x30, X31&& x31, X32&& x32, X33&& x33, X34&& x34, X35&& x35, X36&& x36,
+                Xn&&... xn)
+            {
+                return fold_left_impl<sizeof...(xn) + 1>::apply(
+                    f,
+                    f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(
+                        std::forward<X1> (x1),
+                        std::forward<X2> (x2)),
+                        std::forward<X3> (x3)),
+                        std::forward<X4> (x4)),
+                        std::forward<X5> (x5)),
+                        std::forward<X6> (x6)),
+                        std::forward<X7> (x7)),
+                        std::forward<X8> (x8)),
+                        std::forward<X9> (x9)),
+                        std::forward<X10>(x10)),
+                        std::forward<X11>(x11)),
+                        std::forward<X12>(x12)),
+                        std::forward<X13>(x13)),
+                        std::forward<X14>(x14)),
+                        std::forward<X15>(x15)),
+                        std::forward<X16>(x16)),
+                        std::forward<X17>(x17)),
+                        std::forward<X18>(x18)),
+                        std::forward<X19>(x19)),
+                        std::forward<X20>(x20)),
+                        std::forward<X21>(x21)),
+                        std::forward<X22>(x22)),
+                        std::forward<X23>(x23)),
+                        std::forward<X24>(x24)),
+                        std::forward<X25>(x25)),
+                        std::forward<X26>(x26)),
+                        std::forward<X27>(x27)),
+                        std::forward<X28>(x28)),
+                        std::forward<X29>(x29)),
+                        std::forward<X30>(x30)),
+                        std::forward<X31>(x31)),
+                        std::forward<X32>(x32)),
+                        std::forward<X33>(x33)),
+                        std::forward<X34>(x34)),
+                        std::forward<X35>(x35)),
+                        std::forward<X36>(x36)),
+                    std::forward<Xn>(xn)...
+                );
+            }
+        };
+
+        struct fold_left_t
+        {
+            template<typename F, typename X1, typename... Xn>
+            constexpr auto operator()(F&& f, X1&& x1, Xn&&... xn) const
+                { return fold_left_impl<sizeof...(xn) + 1>::apply(std::forward<F>(f), std::forward<X1>(x1), std::forward<Xn>(xn)...); }
+        };
+    }
+
+    constexpr __impl::fold_left_t fold_left { };
+
+}
+}
+}
\ No newline at end of file
diff --git a/src/cpputils/mp/intern/fold_right.h b/src/cpputils/mp/intern/fold_right.h
new file mode 100644
index 0000000..107bfda
--- /dev/null
+++ b/src/cpputils/mp/intern/fold_right.h
@@ -0,0 +1,244 @@
+#pragma once
+
+#include <utility>
+#include <cpputils/mp/misc/when.h>
+
+namespace utl {
+namespace mp {
+namespace intern {
+
+    namespace __impl
+    {
+        template <unsigned int n, typename = when<true>>
+        struct fold_right_impl;
+
+        template<>
+        struct fold_right_impl<1>
+        {
+            template<typename F, typename X1>
+            static constexpr X1 apply(F&&, X1&& x1)
+                { return std::forward<X1>(x1); }
+        };
+
+        template<>
+        struct fold_right_impl<2>
+        {
+            template<typename F, typename X1, typename X2>
+            static constexpr auto apply(F&& f, X1&& x1, X2&& x2)
+            {
+                return f(
+                    std::forward<X1>(x1),
+                    std::forward<X2>(x2));
+            }
+        };
+
+        template<>
+        struct fold_right_impl<3>
+        {
+            template<typename F, typename X1, typename X2, typename X3>
+            static constexpr auto apply(F&& f, X1&& x1, X2&& x2, X3&& x3)
+            {
+                return f(std::forward<X1>(x1),
+                       f(std::forward<X2>(x2),
+                         std::forward<X3>(x3)));
+            }
+        };
+
+        template<>
+        struct fold_right_impl<4>
+        {
+            template<typename F, typename X1, typename X2, typename X3, typename X4>
+            static constexpr auto apply(F&& f, X1&& x1, X2&& x2, X3&& x3, X4&& x4)
+            {
+                return f(std::forward<X1>(x1),
+                       f(std::forward<X2>(x2),
+                       f(std::forward<X3>(x3),
+                         std::forward<X4>(x4))));
+            }
+        };
+
+        template<>
+        struct fold_right_impl<5>
+        {
+            template<typename F, typename X1, typename X2, typename X3, typename X4, typename X5>
+            static constexpr auto apply(F&& f, X1&& x1, X2&& x2, X3&& x3, X4&& x4, X5&& x5)
+            {
+                return f(std::forward<X1>(x1),
+                       f(std::forward<X2>(x2),
+                       f(std::forward<X3>(x3),
+                       f(std::forward<X4>(x4),
+                         std::forward<X5>(x5)))));
+            }
+        };
+
+        template<>
+        struct fold_right_impl<6>
+        {
+            template<typename F, typename X1, typename X2, typename X3, typename X4, typename X5, typename X6>
+            static constexpr auto apply(F&& f, X1&& x1, X2&& x2, X3&& x3, X4&& x4, X5&& x5, X6&& x6)
+            {
+                return f(std::forward<X1>(x1),
+                       f(std::forward<X2>(x2),
+                       f(std::forward<X3>(x3),
+                       f(std::forward<X4>(x4),
+                       f(std::forward<X5>(x5),
+                         std::forward<X6>(x6))))));
+            }
+        };
+
+        template<>
+        struct fold_right_impl<7>
+        {
+            template<typename F, typename X1, typename X2, typename X3, typename X4, typename X5, typename X6, typename X7>
+            static constexpr auto apply(F&& f, X1&& x1, X2&& x2, X3&& x3, X4&& x4, X5&& x5, X6&& x6, X7&& x7)
+            {
+                return f(std::forward<X1>(x1),
+                       f(std::forward<X2>(x2),
+                       f(std::forward<X3>(x3),
+                       f(std::forward<X4>(x4),
+                       f(std::forward<X5>(x5),
+                       f(std::forward<X6>(x6),
+                         std::forward<X7>(x7)))))));
+            }
+        };
+
+        template<>
+        struct fold_right_impl<8>
+        {
+            template<typename F, typename X1, typename X2, typename X3, typename X4, typename X5, typename X6, typename X7, typename X8>
+            static constexpr auto apply(F&& f, X1&& x1, X2&& x2, X3&& x3, X4&& x4, X5&& x5, X6&& x6, X7&& x7, X8&& x8)
+            {
+                return f(std::forward<X1>(x1),
+                       f(std::forward<X2>(x2),
+                       f(std::forward<X3>(x3),
+                       f(std::forward<X4>(x4),
+                       f(std::forward<X5>(x5),
+                       f(std::forward<X6>(x6),
+                       f(std::forward<X7>(x7),
+                         std::forward<X8>(x8))))))));
+            }
+        };
+
+        template<unsigned int n>
+        struct fold_right_impl<n, when<(n >= 9) && (n < 18)>>
+        {
+            template<typename F, typename X1, typename X2, typename X3, typename X4, typename X5, typename X6, typename X7, typename X8, typename X9, typename... Xn>
+            static constexpr auto apply(F&& f, X1&& x1, X2&& x2, X3&& x3, X4&& x4, X5&& x5, X6&& x6, X7&& x7, X8&& x8, X9&& x9, Xn&&... xn)
+            {
+                return f(std::forward<X1>(x1),
+                       f(std::forward<X2>(x2),
+                       f(std::forward<X3>(x3),
+                       f(std::forward<X4>(x4),
+                       f(std::forward<X5>(x5),
+                       f(std::forward<X6>(x6),
+                       f(std::forward<X7>(x7),
+                       f(std::forward<X8>(x8),
+                         fold_right_impl<sizeof...(xn) + 1>::apply(f, std::forward<X9>(x9), std::forward<Xn>(xn)...)))))))));
+            }
+        };
+
+        template<unsigned int n>
+        struct fold_right_impl<n, when<(n >= 18) && (n < 36)>>
+        {
+            template<
+                typename F,
+                typename X1,  typename X2,  typename X3,  typename X4,  typename X5,  typename X6,  typename X7,  typename X8,  typename X9,
+                typename X10, typename X11, typename X12, typename X13, typename X14, typename X15, typename X16, typename X17, typename X18,
+                typename... Xn>
+            static constexpr auto apply(
+                F&& f,
+                X1&&  x1,  X2&&  x2,  X3&&  x3,  X4&&  x4,  X5&&  x5,  X6&&  x6,  X7&&  x7,  X8&&  x8,  X9&&  x9,
+                X10&& x10, X11&& x11, X12&& x12, X13&& x13, X14&& x14, X15&& x15, X16&& x16, X17&& x17, X18&& x18,
+                Xn&&... xn)
+            {
+                return f(std::forward<X1> (x1),
+                       f(std::forward<X2> (x2),
+                       f(std::forward<X3> (x3),
+                       f(std::forward<X4> (x4),
+                       f(std::forward<X5> (x5),
+                       f(std::forward<X6> (x6),
+                       f(std::forward<X7> (x7),
+                       f(std::forward<X8> (x8),
+                       f(std::forward<X9> (x9),
+                       f(std::forward<X10>(x10),
+                       f(std::forward<X11>(x11),
+                       f(std::forward<X12>(x12),
+                       f(std::forward<X13>(x13),
+                       f(std::forward<X14>(x14),
+                       f(std::forward<X15>(x15),
+                       f(std::forward<X16>(x16),
+                       f(std::forward<X17>(x17),
+                         fold_right_impl<sizeof...(xn) + 1>::apply(f, std::forward<X18>(x18), std::forward<Xn>(xn)...))))))))))))))))));
+            }
+        };
+
+        template<unsigned int n>
+        struct fold_right_impl<n, when<(n >= 36)>>
+        {
+            template<
+                typename F,
+                typename X1,  typename X2,  typename X3,  typename X4,  typename X5,  typename X6,  typename X7,  typename X8,  typename X9,
+                typename X10, typename X11, typename X12, typename X13, typename X14, typename X15, typename X16, typename X17, typename X18,
+                typename X19, typename X20, typename X21, typename X22, typename X23, typename X24, typename X25, typename X26, typename X27,
+                typename X28, typename X29, typename X30, typename X31, typename X32, typename X33, typename X34, typename X35, typename X36,
+                typename... Xn>
+            static constexpr auto apply(
+                F&& f,
+                X1&&  x1,  X2&&  x2,  X3&&  x3,  X4&&  x4,  X5&&  x5,  X6&&  x6,  X7&&  x7,  X8&&  x8,  X9&&  x9,
+                X10&& x10, X11&& x11, X12&& x12, X13&& x13, X14&& x14, X15&& x15, X16&& x16, X17&& x17, X18&& x18,
+                X19&& x19, X20&& x20, X21&& x21, X22&& x22, X23&& x23, X24&& x24, X25&& x25, X26&& x26, X27&& x27,
+                X28&& x28, X29&& x29, X30&& x30, X31&& x31, X32&& x32, X33&& x33, X34&& x34, X35&& x35, X36&& x36,
+                Xn&&... xn)
+            {
+                return f(std::forward<X1> (x1),
+                       f(std::forward<X2> (x2),
+                       f(std::forward<X3> (x3),
+                       f(std::forward<X4> (x4),
+                       f(std::forward<X5> (x5),
+                       f(std::forward<X6> (x6),
+                       f(std::forward<X7> (x7),
+                       f(std::forward<X8> (x8),
+                       f(std::forward<X9> (x9),
+                       f(std::forward<X10>(x10),
+                       f(std::forward<X11>(x11),
+                       f(std::forward<X12>(x12),
+                       f(std::forward<X13>(x13),
+                       f(std::forward<X14>(x14),
+                       f(std::forward<X15>(x15),
+                       f(std::forward<X16>(x16),
+                       f(std::forward<X17>(x17),
+                       f(std::forward<X18>(x18),
+                       f(std::forward<X19>(x19),
+                       f(std::forward<X20>(x20),
+                       f(std::forward<X21>(x21),
+                       f(std::forward<X22>(x22),
+                       f(std::forward<X23>(x23),
+                       f(std::forward<X24>(x24),
+                       f(std::forward<X25>(x25),
+                       f(std::forward<X26>(x26),
+                       f(std::forward<X27>(x27),
+                       f(std::forward<X28>(x28),
+                       f(std::forward<X29>(x29),
+                       f(std::forward<X30>(x30),
+                       f(std::forward<X31>(x31),
+                       f(std::forward<X32>(x32),
+                       f(std::forward<X33>(x33),
+                       f(std::forward<X34>(x34),
+                       f(std::forward<X35>(x35),
+                         fold_right_impl<sizeof...(xn) + 1>::apply(f, std::forward<X36>(x36), std::forward<Xn>(xn)...))))))))))))))))))))))))))))))))))));
+            }
+        };
+
+        struct fold_right_t
+        {
+            template<typename F, typename X1, typename... Xn>
+            constexpr auto operator()(F&& f, X1&& x1, Xn&&... xn) const
+                { return fold_right_impl<sizeof...(xn) + 1>::apply(std::forward<F>(f), std::forward<X1>(x1), std::forward<Xn>(xn)...); }
+        };
+    }
+
+    constexpr __impl::fold_right_t fold_right { };
+
+}
+}
+}
\ No newline at end of file
diff --git a/src/cpputils/mp/intern/has_value.h b/src/cpputils/mp/intern/has_value.h
index 11a94aa..525d9aa 100644
--- a/src/cpputils/mp/intern/has_value.h
+++ b/src/cpputils/mp/intern/has_value.h
@@ -8,9 +8,9 @@ namespace intern {
 
     template<typename C>
     struct has_value
-        : c_bool<!is_default<__impl::value_impl<tag_of<C>>>::value>
+        : c_bool_t<!is_default<::utl::mp::__impl::value_impl<tag_of<C>>>::value>
         { };
 
 }
 }
-}
\ No newline at end of file
+}
diff --git a/src/cpputils/mp/intern/hash_table.h b/src/cpputils/mp/intern/hash_table.h
new file mode 100644
index 0000000..2fbbfc8
--- /dev/null
+++ b/src/cpputils/mp/intern/hash_table.h
@@ -0,0 +1,61 @@
+#pragma once
+
+#include <cpputils/mp/operations/hash.h>
+#include <cpputils/mp/operations/compare/equal.h>
+
+namespace utl {
+namespace mp {
+namespace intern {
+
+    namespace __impl
+    {
+        template<typename H, size_t... I>
+        struct bucket { };
+
+        template<typename... Buckets>
+        struct hash_table
+            : Buckets...
+            { };
+
+        /* find indices */
+        template<typename Hash, size_t... I>
+        std::index_sequence<I...> find_indices_impl(const bucket<Hash, I...>&);
+
+        template<typename Hash>
+        std::index_sequence<> find_indices_impl(...);
+
+        /* find index */
+        template<template<size_t> class KeyAtIndex, typename Key>
+        struct find_pred
+        {
+            template<typename Index>
+            auto operator()(const Index&) const ->
+                decltype(equal(std::declval<KeyAtIndex<Index::value>>(), std::declval<Key>()));
+        };
+
+        template<typename Indices, typename Key, template<size_t> class KeyAtIndex>
+        struct find_index_impl
+            { using type = decltype(find_if(Indices { }, find_pred<KeyAtIndex, Key> { })); };
+    }
+
+    template<typename Map, typename Key>
+    struct find_indices
+    {
+        using hash = typename decltype(hash(std::declval<Key>()))::type;
+        using type = decltype(__impl::find_indices_impl<hash>(std::declval<Map>()));
+    };
+
+    template<template<size_t> class KeyAtIndex, size_t N, typename Indices = std::make_index_sequence<N>>
+    struct make_hash_table;
+
+    template<template<size_t> class KeyAtIndex, size_t N, size_t... I>
+    struct make_hash_table<KeyAtIndex, N, std::index_sequence<I...>>
+    {
+        using type = __impl::hash_table<
+            __impl::bucket<typename decltype(hash(std::declval<KeyAtIndex<I>>()))::type, I>...
+        >;
+    };
+
+}
+}
+}
\ No newline at end of file
diff --git a/src/cpputils/mp/intern/operators_comparable.h b/src/cpputils/mp/intern/operators_comparable.h
index 353f34f..75bd8fb 100644
--- a/src/cpputils/mp/intern/operators_comparable.h
+++ b/src/cpputils/mp/intern/operators_comparable.h
@@ -2,7 +2,7 @@
 
 #include <utility>
 #include <cpputils/mp/core/conditionals.h>
-#include <cpputils/mp/util/tag_of.h>
+#include <cpputils/mp/misc/tag_of.h>
 #include <cpputils/mp/operations/compare/equal.h>
 #include <cpputils/mp/operations/compare/not_equal.h>
 
diff --git a/src/cpputils/mp/intern/operators_orderable.h b/src/cpputils/mp/intern/operators_orderable.h
index 7cf3514..18e270b 100644
--- a/src/cpputils/mp/intern/operators_orderable.h
+++ b/src/cpputils/mp/intern/operators_orderable.h
@@ -2,7 +2,7 @@
 
 #include <utility>
 #include <cpputils/mp/core/conditionals.h>
-#include <cpputils/mp/util/tag_of.h>
+#include <cpputils/mp/misc/tag_of.h>
 #include <cpputils/mp/operations/compare/less.h>
 #include <cpputils/mp/operations/compare/less_equal.h>
 #include <cpputils/mp/operations/compare/greater.h>
diff --git a/src/cpputils/mp/misc.h b/src/cpputils/mp/misc.h
new file mode 100644
index 0000000..5ae860f
--- /dev/null
+++ b/src/cpputils/mp/misc.h
@@ -0,0 +1,8 @@
+#pragma once
+
+#include <cpputils/mp/misc/default.h>
+#include <cpputils/mp/misc/is_a.h>
+#include <cpputils/mp/misc/make.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/to.h>
\ No newline at end of file
diff --git a/src/cpputils/mp/util/default.h b/src/cpputils/mp/misc/default.h
similarity index 91%
rename from src/cpputils/mp/util/default.h
rename to src/cpputils/mp/misc/default.h
index 933513d..e5c9659 100644
--- a/src/cpputils/mp/util/default.h
+++ b/src/cpputils/mp/misc/default.h
@@ -20,12 +20,12 @@ namespace mp {
 
         template<typename T, typename>
         struct is_default_impl :
-            public c_false
+            public c_false_t
             { };
 
         template<typename T>
         struct is_default_impl<T, decltype((void)static_cast<default_>(std::declval<T>()))> :
-            public c_true
+            public c_true_t
             { };
    }
 
diff --git a/src/cpputils/mp/util/is_a.h b/src/cpputils/mp/misc/is_a.h
similarity index 91%
rename from src/cpputils/mp/util/is_a.h
rename to src/cpputils/mp/misc/is_a.h
index e48ebec..e0ace0b 100644
--- a/src/cpputils/mp/util/is_a.h
+++ b/src/cpputils/mp/misc/is_a.h
@@ -1,7 +1,7 @@
 #pragma once
 
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/tag_of.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
 
 namespace utl {
 namespace mp {
diff --git a/src/cpputils/mp/util/make.h b/src/cpputils/mp/misc/make.h
similarity index 94%
rename from src/cpputils/mp/util/make.h
rename to src/cpputils/mp/misc/make.h
index 624c5e4..60dad4a 100644
--- a/src/cpputils/mp/util/make.h
+++ b/src/cpputils/mp/misc/make.h
@@ -2,8 +2,8 @@
 #pragma once
 
 #include <utility>
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/default.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/default.h>
 
 namespace utl {
 namespace mp {
diff --git a/src/cpputils/mp/util/tag_of.h b/src/cpputils/mp/misc/tag_of.h
similarity index 95%
rename from src/cpputils/mp/util/tag_of.h
rename to src/cpputils/mp/misc/tag_of.h
index 72d94a2..a75cda9 100644
--- a/src/cpputils/mp/util/tag_of.h
+++ b/src/cpputils/mp/misc/tag_of.h
@@ -1,7 +1,7 @@
 #pragma once
 
 #include <cpputils/mp/core/modifier.h>
-#include <cpputils/mp/util/when.h>
+#include <cpputils/mp/misc/when.h>
 
 namespace utl {
 namespace mp {
diff --git a/src/cpputils/mp/util/to.h b/src/cpputils/mp/misc/to.h
similarity index 98%
rename from src/cpputils/mp/util/to.h
rename to src/cpputils/mp/misc/to.h
index 928e516..e7f00b2 100644
--- a/src/cpputils/mp/util/to.h
+++ b/src/cpputils/mp/misc/to.h
@@ -1,7 +1,7 @@
 #pragma once
 
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/tag_of.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
 #include <cpputils/mp/core/conditionals.h>
 
 namespace utl {
diff --git a/src/cpputils/mp/util/when.h b/src/cpputils/mp/misc/when.h
similarity index 94%
rename from src/cpputils/mp/util/when.h
rename to src/cpputils/mp/misc/when.h
index 8c87252..d62e216 100644
--- a/src/cpputils/mp/util/when.h
+++ b/src/cpputils/mp/misc/when.h
@@ -24,7 +24,7 @@ namespace mp {
     {
         template<typename...>
         struct wrong_impl :
-            public c_false
+            public c_false_t
             { };
    }
 
diff --git a/src/cpputils/mp/operations.h b/src/cpputils/mp/operations.h
index c0c84fe..75a2286 100644
--- a/src/cpputils/mp/operations.h
+++ b/src/cpputils/mp/operations.h
@@ -1,6 +1,15 @@
 #pragma once
 
+#include <cpputils/mp/operations/at.h>
+#include <cpputils/mp/operations/compare.h>
+#include <cpputils/mp/operations/eval_if.h>
+#include <cpputils/mp/operations/eval.h>
 #include <cpputils/mp/operations/first.h>
+#include <cpputils/mp/operations/hash.h>
+#include <cpputils/mp/operations/if.h>
+#include <cpputils/mp/operations/length.h>
+#include <cpputils/mp/operations/logical.h>
 #include <cpputils/mp/operations/second.h>
-#include <cpputils/mp/operations/compare.h>
-#include <cpputils/mp/operations/logical.h>
\ No newline at end of file
+#include <cpputils/mp/operations/transform.h>
+#include <cpputils/mp/operations/unpack.h>
+#include <cpputils/mp/operations/value.h>
\ No newline at end of file
diff --git a/src/cpputils/mp/operations/at.h b/src/cpputils/mp/operations/at.h
new file mode 100644
index 0000000..df2416b
--- /dev/null
+++ b/src/cpputils/mp/operations/at.h
@@ -0,0 +1,52 @@
+#pragma once
+
+#include <utility>
+#include <cpputils/mp/core/const.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
+
+namespace utl {
+namespace mp {
+
+    namespace __impl
+    {
+        struct at_t
+        {
+            template<typename Xs, typename N>
+            constexpr auto operator()(Xs&& xs, const N& n) const;
+        };
+    }
+
+    constexpr __impl::at_t at { };
+
+    template<size_t N, typename Xs>
+    constexpr auto at_c(Xs&& xs)
+        { return at(std::forward<Xs>(xs), c_size_t<N> { }); }
+
+    namespace __impl
+    {
+        template <typename T, typename = void>
+        struct at_impl 
+            : at_impl<T, when<true>>
+            { };
+
+        template <typename T, bool condition>
+        struct at_impl<T, when<condition>>
+            : default_
+        {
+            template <typename ...Args>
+            static constexpr auto apply(Args&& ...) = delete;
+        };
+
+        template<typename Xs, typename N>
+        constexpr auto at_t::operator()(Xs&& xs, const N& n) const
+        {
+            using tag_type     = tag_of<Xs>;
+            using at_impl_type = at_impl<tag_type>;
+            return at_impl_type::apply(std::forward<Xs>(xs), n);
+        }
+    }
+
+}
+}
\ No newline at end of file
diff --git a/src/cpputils/mp/operations/compare/equal.h b/src/cpputils/mp/operations/compare/equal.h
index 6ae499a..32635a0 100644
--- a/src/cpputils/mp/operations/compare/equal.h
+++ b/src/cpputils/mp/operations/compare/equal.h
@@ -1,9 +1,9 @@
 #pragma once
 
 #include <cpputils/mp/core/const.h>
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/tag_of.h>
-#include <cpputils/mp/util/default.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
 #include <cpputils/mp/intern/has_value.h>
 #include <cpputils/mp/intern/comparable_equal.h>
 #include <cpputils/mp/operations/if.h>
@@ -36,7 +36,7 @@ namespace mp {
         {
             template <typename ...Args>
             static constexpr auto apply(Args&& ...)
-                { return c_false { }; }
+                { return c_false; }
         };
 
         template <typename T, typename U>
@@ -55,7 +55,7 @@ namespace mp {
             {
                 constexpr auto eq          = equal(value<X>(), value<Y>());
                 constexpr bool truth_value = if_  (eq, true, false);
-                return c_bool<truth_value> { };
+                return c_bool_t<truth_value> { };
             }
         };
 
diff --git a/src/cpputils/mp/operations/compare/greater.h b/src/cpputils/mp/operations/compare/greater.h
index 3778d68..e8e129c 100644
--- a/src/cpputils/mp/operations/compare/greater.h
+++ b/src/cpputils/mp/operations/compare/greater.h
@@ -1,9 +1,9 @@
 #pragma once
 
 #include <cpputils/mp/core/const.h>
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/tag_of.h>
-#include <cpputils/mp/util/default.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
 #include <cpputils/mp/operations/logical/not.h>
 #include <cpputils/mp/operations/compare/less.h>
 
diff --git a/src/cpputils/mp/operations/compare/greater_equal.h b/src/cpputils/mp/operations/compare/greater_equal.h
index 5edb04e..d78bdc2 100644
--- a/src/cpputils/mp/operations/compare/greater_equal.h
+++ b/src/cpputils/mp/operations/compare/greater_equal.h
@@ -1,9 +1,9 @@
 #pragma once
 
 #include <cpputils/mp/core/const.h>
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/tag_of.h>
-#include <cpputils/mp/util/default.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
 #include <cpputils/mp/operations/logical/not.h>
 #include <cpputils/mp/operations/compare/less.h>
 
diff --git a/src/cpputils/mp/operations/compare/less.h b/src/cpputils/mp/operations/compare/less.h
index 0241226..23ca38f 100644
--- a/src/cpputils/mp/operations/compare/less.h
+++ b/src/cpputils/mp/operations/compare/less.h
@@ -1,9 +1,9 @@
 #pragma once
 
 #include <cpputils/mp/core/const.h>
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/tag_of.h>
-#include <cpputils/mp/util/default.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
 #include <cpputils/mp/intern/has_value.h>
 #include <cpputils/mp/intern/comparable_less.h>
 #include <cpputils/mp/operations/if.h>
@@ -36,7 +36,7 @@ namespace mp {
         {
             template <typename ...Args>
             static constexpr auto apply(Args&& ...)
-                { return c_false { }; }
+                { return c_false; }
         };
 
         template <typename T, typename U>
@@ -55,7 +55,7 @@ namespace mp {
             {
                 constexpr auto eq          = less(value<X>(), value<Y>());
                 constexpr bool truth_value = if_  (eq, true, false);
-                return c_bool<truth_value> { };
+                return c_bool_t<truth_value> { };
             }
         };
 
diff --git a/src/cpputils/mp/operations/compare/less_equal.h b/src/cpputils/mp/operations/compare/less_equal.h
index 2b91092..6f012ad 100644
--- a/src/cpputils/mp/operations/compare/less_equal.h
+++ b/src/cpputils/mp/operations/compare/less_equal.h
@@ -1,9 +1,9 @@
 #pragma once
 
 #include <cpputils/mp/core/const.h>
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/tag_of.h>
-#include <cpputils/mp/util/default.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
 #include <cpputils/mp/operations/logical/not.h>
 #include <cpputils/mp/operations/compare/less.h>
 
diff --git a/src/cpputils/mp/operations/compare/not_equal.h b/src/cpputils/mp/operations/compare/not_equal.h
index cabd242..74cee42 100644
--- a/src/cpputils/mp/operations/compare/not_equal.h
+++ b/src/cpputils/mp/operations/compare/not_equal.h
@@ -1,9 +1,9 @@
 #pragma once
 
 #include <cpputils/mp/core/const.h>
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/tag_of.h>
-#include <cpputils/mp/util/default.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
 #include <cpputils/mp/operations/logical/not.h>
 #include <cpputils/mp/operations/compare/not_equal.h>
 
diff --git a/src/cpputils/mp/operations/eval.h b/src/cpputils/mp/operations/eval.h
index fab02a6..568cc84 100644
--- a/src/cpputils/mp/operations/eval.h
+++ b/src/cpputils/mp/operations/eval.h
@@ -1,9 +1,9 @@
 #pragma once
 
 #include <utility>
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/tag_of.h>
-#include <cpputils/mp/util/default.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
 
 namespace utl {
 namespace mp {
diff --git a/src/cpputils/mp/operations/eval_if.h b/src/cpputils/mp/operations/eval_if.h
index a1b77e6..c4f15b4 100644
--- a/src/cpputils/mp/operations/eval_if.h
+++ b/src/cpputils/mp/operations/eval_if.h
@@ -1,8 +1,8 @@
 #pragma once
 
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/tag_of.h>
-#include <cpputils/mp/util/default.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
 #include <cpputils/mp/intern/has_value.h>
 #include <cpputils/mp/operations/if.fwd.h>
 #include <cpputils/mp/operations/eval.h>
@@ -51,11 +51,11 @@ namespace mp {
         struct eval_if_impl<T, when<intern::has_value<T>::value>>
         {
             template<typename Then, typename Else>
-            static constexpr auto eval_if_helper(c_true, Then&& t, Else&& e)
+            static constexpr auto eval_if_helper(c_true_t, Then&& t, Else&& e)
                 { return eval(std::forward<Then>(t)); }
 
             template<typename Then, typename Else>
-            static constexpr auto eval_if_helper(c_false, Then&& t, Else&& e)
+            static constexpr auto eval_if_helper(c_false_t, Then&& t, Else&& e)
                 { return eval(std::forward<Else>(e)); }
 
             template <typename Cond, typename Then, typename Else>
@@ -63,7 +63,7 @@ namespace mp {
             {
                 constexpr auto cond = value<Cond>();
                 constexpr bool truth_value = if_(cond, true, false);
-                return eval_if_helper(c_bool<truth_value> { }, std::forward<Then>(t), std::forward<Else>(e));
+                return eval_if_helper(c_bool_t<truth_value> { }, std::forward<Then>(t), std::forward<Else>(e));
             }
         };
 
diff --git a/src/cpputils/mp/operations/first.h b/src/cpputils/mp/operations/first.h
index 5cc75ca..7d44334 100644
--- a/src/cpputils/mp/operations/first.h
+++ b/src/cpputils/mp/operations/first.h
@@ -1,8 +1,8 @@
 #pragma once
 
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/tag_of.h>
-#include <cpputils/mp/util/default.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
 
 namespace utl {
 namespace mp {
diff --git a/src/cpputils/mp/operations/hash.fwd.h b/src/cpputils/mp/operations/hash.fwd.h
new file mode 100644
index 0000000..62b808a
--- /dev/null
+++ b/src/cpputils/mp/operations/hash.fwd.h
@@ -0,0 +1,28 @@
+#pragma once
+
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
+#include <cpputils/mp/core/const.h>
+#include <cpputils/mp/core/modifier.h>
+#include <cpputils/mp/container/type.h>
+
+namespace utl {
+namespace mp {
+
+    namespace __impl /* forward declaration */
+    {
+        struct hash_t
+        {
+            template<typename X>
+            constexpr auto operator()(const X& x) const;
+        };
+
+        template <typename T, typename = void>
+        struct hash_impl;
+    }
+
+    constexpr __impl::hash_t hash { };
+
+}
+}
\ No newline at end of file
diff --git a/src/cpputils/mp/operations/hash.h b/src/cpputils/mp/operations/hash.h
new file mode 100644
index 0000000..cb4ac22
--- /dev/null
+++ b/src/cpputils/mp/operations/hash.h
@@ -0,0 +1,104 @@
+#pragma once
+
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
+#include <cpputils/mp/core/const.h>
+#include <cpputils/mp/core/modifier.h>
+#include <cpputils/mp/core/conditionals.h>
+#include <cpputils/mp/container/type.h>
+#include <cpputils/mp/operations/hash.fwd.h>
+
+namespace utl {
+namespace mp {
+
+    namespace __impl /* implementation */
+    {
+        template <typename T, typename = void>
+        struct hash_integral_helper;
+
+        template <typename Member, typename T>
+        struct hash_integral_helper<Member T::*>
+        {
+            template <typename X>
+            static constexpr auto apply(X const&)
+                { return type_c<integral_constant<Member T::*, X::value>>; }
+        };
+
+        template <typename T>
+        struct hash_integral_helper<T, enable_if<is_signed<T>>>
+        {
+            template <typename X>
+            static constexpr auto apply(X const&)
+            {
+                constexpr signed long long x = X::value;
+                return type_c<integral_constant<signed long long, x>>;
+            }
+        };
+
+        template <typename T>
+        struct hash_integral_helper<T, enable_if<is_unsigned<T>>>
+        {
+            template <typename X>
+            static constexpr auto apply(X const&)
+            {
+                constexpr unsigned long long x = X::value;
+                return type_c<integral_constant<unsigned long long, x>>;
+            }
+        };
+
+        template <>
+        struct hash_integral_helper<bool>
+        {
+            template <typename X>
+            static constexpr auto apply(X const&)
+                { return type_c<c_bool_t<X::value>>; }
+        };
+
+        template <>
+        struct hash_integral_helper<char>
+        {
+            template <typename X>
+            static constexpr auto apply(X const&)
+            {
+                using T = if_c<is_signed<char>::value, signed long long, unsigned long long>;
+                constexpr T x = X::value;
+                return type_c<integral_constant<T, x>>;
+            }
+        };
+
+        template <typename T, typename>
+        struct hash_impl
+            : hash_impl<T, when<true>>
+            { };
+
+        template <typename Tag, bool condition>
+        struct hash_impl<Tag, when<condition>>
+            : default_
+        {
+            template <typename X>
+            static constexpr auto apply(X const&) = delete;
+        };
+
+        template <typename T>
+        struct hash_impl<tag_integral_constant<T>, when<true>>
+        {
+            template<typename X>
+            static constexpr auto apply(const X& x)
+            {
+                using type = remove_cv<decltype(X::value)>;
+                return hash_integral_helper<type>::apply(x);
+            }
+        };
+
+        template<typename X>
+        constexpr auto hash_t::operator()(const X& x) const
+        {
+            using tag_type = tag_of<X>;
+            using hash_impl_type = hash_impl<tag_type>;
+            return hash_impl_type::apply(x);
+        }
+    }
+
+}
+}
\ No newline at end of file
diff --git a/src/cpputils/mp/operations/if.h b/src/cpputils/mp/operations/if.h
index 5cfac9c..afcd4d3 100644
--- a/src/cpputils/mp/operations/if.h
+++ b/src/cpputils/mp/operations/if.h
@@ -2,9 +2,9 @@
 
 #include <cpputils/mp/operations/if.fwd.h>
 
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/tag_of.h>
-#include <cpputils/mp/util/default.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
 #include <cpputils/mp/operations/eval_if.h>
 
 namespace utl {
diff --git a/src/cpputils/mp/operations/length.h b/src/cpputils/mp/operations/length.h
new file mode 100644
index 0000000..3c403d3
--- /dev/null
+++ b/src/cpputils/mp/operations/length.h
@@ -0,0 +1,56 @@
+#pragma once
+
+#include <cpputils/mp/core/const.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
+#include <cpputils/mp/operations/unpack.fwd.h>
+
+namespace utl {
+namespace mp {
+
+    namespace __impl
+    {
+        struct length_t
+        {
+            template<typename Xs>
+            constexpr auto operator()(const Xs& xs) const;
+        };
+    }
+
+    constexpr __impl::length_t length { };
+
+    namespace __impl
+    {
+        struct length_argn
+        {
+            template<typename... Xn>
+            constexpr c_size_t<sizeof...(Xn)> operator()(const Xn& ...) const
+                { return { }; }
+        };
+
+        template <typename T, typename = void>
+        struct length_impl
+            : length_impl<T, when<true>>
+            { };
+
+        template<typename T, bool condition>
+        struct length_impl<T, when<condition>>
+            : default_
+        {
+            template<typename Xs>
+            static constexpr auto apply(const Xs& xs)
+                { return unpack(xs, length_argn { }); }
+        };
+
+        template<typename Xs>
+        constexpr auto length_t::operator()(const Xs& xs) const
+        {
+            using tag_type         = tag_of<Xs>;
+            using length_impl_type = length_impl<tag_type>;
+            return length_impl_type::apply(xs);
+        }
+    }
+
+}
+}
\ No newline at end of file
diff --git a/src/cpputils/mp/operations/logical/and.h b/src/cpputils/mp/operations/logical/and.h
index e7ab46c..ed011f4 100644
--- a/src/cpputils/mp/operations/logical/and.h
+++ b/src/cpputils/mp/operations/logical/and.h
@@ -1,10 +1,11 @@
 #pragma once
 
 #include <cpputils/mp/core/const.h>
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/tag_of.h>
-#include <cpputils/mp/util/default.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
 #include <cpputils/mp/operations/if.h>
+#include <cpputils/mp/intern/fold_left.h>
 
 namespace utl {
 namespace mp {
@@ -46,17 +47,16 @@ namespace mp {
             using and_impl_type = and_impl<tag_type>;
             return and_impl_type::apply(std::forward<X>(x), std::forward<Y>(y));
         };
-        /* TODO
+        
         template <typename X, typename ...Y>
         constexpr auto and_t::operator()(X&& x, Y&& ...y) const
         {
-            return detail::variadic::foldl1(
+            return intern::fold_left(
                 *this,
                 static_cast<X&&>(x),
                 static_cast<Y&&>(y)...
             );
         }
-        */
     }
 
 }
diff --git a/src/cpputils/mp/operations/logical/not.h b/src/cpputils/mp/operations/logical/not.h
index dd29455..d2f3de4 100644
--- a/src/cpputils/mp/operations/logical/not.h
+++ b/src/cpputils/mp/operations/logical/not.h
@@ -1,9 +1,9 @@
 #pragma once
 
 #include <cpputils/mp/core/const.h>
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/tag_of.h>
-#include <cpputils/mp/util/default.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
 
 namespace utl {
 namespace mp {
diff --git a/src/cpputils/mp/operations/logical/or.h b/src/cpputils/mp/operations/logical/or.h
index 5805cd9..bb703ec 100644
--- a/src/cpputils/mp/operations/logical/or.h
+++ b/src/cpputils/mp/operations/logical/or.h
@@ -1,10 +1,11 @@
 #pragma once
 
 #include <cpputils/mp/core/const.h>
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/tag_of.h>
-#include <cpputils/mp/util/default.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
 #include <cpputils/mp/operations/if.h>
+#include <cpputils/mp/intern/fold_left.h>
 
 namespace utl {
 namespace mp {
@@ -46,17 +47,16 @@ namespace mp {
             using or_impl_type = or_impl<tag_type>;
             return or_impl_type::apply(std::forward<X>(x), std::forward<Y>(y));
         };
-        /* TODO
+
         template <typename X, typename ...Y>
         constexpr auto or_t::operator()(X&& x, Y&& ...y) const
         {
-            return detail::variadic::foldl1(
+            return intern::fold_left(
                 *this,
                 static_cast<X&&>(x),
                 static_cast<Y&&>(y)...
             );
         }
-        */
     }
 
 }
diff --git a/src/cpputils/mp/operations/second.h b/src/cpputils/mp/operations/second.h
index 80e925f..e36b4f4 100644
--- a/src/cpputils/mp/operations/second.h
+++ b/src/cpputils/mp/operations/second.h
@@ -1,8 +1,8 @@
 #pragma once
 
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/tag_of.h>
-#include <cpputils/mp/util/default.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
 
 namespace utl {
 namespace mp {
diff --git a/src/cpputils/mp/operations/transform.h b/src/cpputils/mp/operations/transform.h
new file mode 100644
index 0000000..66f0ca2
--- /dev/null
+++ b/src/cpputils/mp/operations/transform.h
@@ -0,0 +1,68 @@
+#pragma once
+
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/make.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
+#include <cpputils/mp/operations/unpack.h>
+
+namespace utl {
+namespace mp {
+
+    namespace __impl
+    {
+        struct transform_t
+        {
+            template<typename Xs, typename F>
+            constexpr auto operator()(Xs&& xs, F&& f) const;
+        };
+    }
+
+    constexpr __impl::transform_t transform { };
+
+    namespace __impl
+    {
+        template<typename Xs, typename = void>
+        struct transform_impl
+            : transform_impl<Xs, when<true>>
+            { };
+
+        template<typename T, bool condition>
+        struct transform_impl<T, when<condition>>
+            : default_
+        {
+            template<typename Xs, typename F>  
+            static constexpr auto apply(Xs&& xs, F&& f) = delete;
+        };
+
+        template<typename T>
+        struct transform_impl<T, when<!is_default<unpack_impl<tag_of<T>>>::value>>
+        {
+            using tag_type = tag_of<T>;
+
+            template<typename F>
+            struct transformer
+            {
+                F f;
+
+                template<typename... Xn>
+                constexpr auto operator()(Xn&&... xn) const
+                    { return make<tag_type>((*f)(std::forward<Xn>(xn))...); }
+            };
+
+            template<typename Xs, typename F>
+            static constexpr auto apply(Xs&& xs, F&& f)
+                { return unpack(std::forward<Xs>(xs), transformer<decltype(&f)> { &f }); }
+        };
+
+        template<typename Xs, typename F>
+        constexpr auto transform_t::operator()(Xs&& xs, F&& f) const
+        {
+            using tag_type = tag_of<Xs>;
+            using transform_impl_type = transform_impl<tag_type>;
+            return transform_impl_type::apply(std::forward<Xs>(xs), std::forward<F>(f));
+        }
+    }
+
+}
+}
\ No newline at end of file
diff --git a/src/cpputils/mp/operations/unpack.fwd.h b/src/cpputils/mp/operations/unpack.fwd.h
new file mode 100644
index 0000000..0762757
--- /dev/null
+++ b/src/cpputils/mp/operations/unpack.fwd.h
@@ -0,0 +1,18 @@
+#pragma once
+
+namespace utl {
+namespace mp {
+
+    namespace __impl
+    {
+        struct unpack_t
+        {
+            template<typename Xs, typename F>
+            constexpr auto operator()(Xs&& xs, F&& f) const;
+        };
+    }
+
+    constexpr __impl::unpack_t unpack { };
+
+}
+}
\ No newline at end of file
diff --git a/src/cpputils/mp/operations/unpack.h b/src/cpputils/mp/operations/unpack.h
new file mode 100644
index 0000000..21ed420
--- /dev/null
+++ b/src/cpputils/mp/operations/unpack.h
@@ -0,0 +1,61 @@
+#pragma once
+
+#include <utility>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
+#include <cpputils/mp/operations/at.h>
+#include <cpputils/mp/operations/length.h>
+#include <cpputils/mp/operations/unpack.fwd.h>
+
+namespace utl {
+namespace mp {
+
+    namespace __impl
+    {
+        template<typename T, typename = void>
+        struct unpack_impl
+            : unpack_impl<T, when<true>>
+            { };
+
+        template<typename T>
+        struct unpack_impl<T, when<
+            !is_default<length_impl<tag_of<T>>>::value &&
+            !is_default<at_impl    <tag_of<T>>>::value>>
+        {
+            template<typename Xs, typename F, size_t... I>
+            static constexpr auto unpack_helper(Xs&& xs, F&& f, std::index_sequence<I...>)
+                { return std::forward<F>(f)(at_c<I>(std::forward<Xs>(xs))...); }
+
+            template<typename Xs, typename F>
+            static constexpr auto apply(Xs&& xs, F&& f)
+            {
+                constexpr size_t N = decltype(length(xs))::value;
+                return unpack_helper(std::forward<Xs>(xs), std::forward<F>(f), std::make_index_sequence<N> { });
+            }
+        };
+
+        template<typename T, size_t N>
+        struct unpack_impl<T[N]>
+        {
+            template<typename Xs, typename F, size_t... I>
+            static constexpr auto unpack_helper(Xs&& xs, F&& f, std::index_sequence<I...>) 
+                { return std::forward<F>(f)(std::forward<Xs>(xs)[I]...); }
+            
+            template<typename Xs, typename F>
+            static constexpr auto apply(Xs&& xs, F&& f)
+                { return unpack_helper(std::forward<Xs>(xs), std::forward<F>(f), std::make_index_sequence<N> { }); }
+        };
+
+        // TODO: Pair, Struct
+
+        template<typename Xs, typename F>
+        constexpr auto unpack_t::operator()(Xs&& xs, F&& f) const
+        {
+            using tag_type         = tag_of<Xs>;
+            using unpack_impl_type = unpack_impl<tag_type>;
+            return unpack_impl_type::apply(std::forward<Xs>(xs), std::forward<F>(f));
+        }
+    }
+
+}
+}
\ No newline at end of file
diff --git a/src/cpputils/mp/operations/value.h b/src/cpputils/mp/operations/value.h
index ab9975f..dde7adc 100644
--- a/src/cpputils/mp/operations/value.h
+++ b/src/cpputils/mp/operations/value.h
@@ -1,8 +1,8 @@
 #pragma once
 
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/tag_of.h>
-#include <cpputils/mp/util/default.h>
+#include <cpputils/mp/misc/when.h>
+#include <cpputils/mp/misc/tag_of.h>
+#include <cpputils/mp/misc/default.h>
 
 namespace utl {
 namespace mp {
@@ -42,7 +42,7 @@ namespace mp {
         };
 
         template <typename T>
-        struct value_impl<tag_const<T>>
+        struct value_impl<tag_integral_constant<T>>
         {
             template <typename C>
             static constexpr auto apply()
diff --git a/src/cpputils/mp/util.h b/src/cpputils/mp/util.h
deleted file mode 100644
index d5ff0bc..0000000
--- a/src/cpputils/mp/util.h
+++ /dev/null
@@ -1,8 +0,0 @@
-#pragma once
-
-#include <cpputils/mp/util/default.h>
-#include <cpputils/mp/util/is_a.h>
-#include <cpputils/mp/util/make.h>
-#include <cpputils/mp/util/tag_of.h>
-#include <cpputils/mp/util/when.h>
-#include <cpputils/mp/util/to.h>
\ No newline at end of file
diff --git a/test/mp/container/basic_tuple.cpp b/test/mp/container/basic_tuple.cpp
new file mode 100644
index 0000000..ed926ad
--- /dev/null
+++ b/test/mp/container/basic_tuple.cpp
@@ -0,0 +1,41 @@
+#include <cpputils/mp/core/const.h>
+#include <cpputils/mp/container/basic_tuple.h>
+
+using namespace ::utl::mp;
+
+namespace test_mp_container_basic_tuple
+{
+    struct op_unpack
+    {
+        constexpr auto operator()(const c_bool_t<false>&, const c_size_t<5>&)
+            { return true; }
+    };
+
+    template<typename T>
+    struct Wrapper { };
+
+    struct op_transform
+    {
+        template<typename T>
+        constexpr auto operator()(T&& t)
+            { return Wrapper<clean_type<T>> { }; }
+    };
+
+    constexpr auto my_tuple = make_basic_tuple(c_bool_t<false> { }, c_size_t<5> { });
+    constexpr c_size_t<0> index0;
+    constexpr c_size_t<1> index1;
+
+    static_assert(unpack(my_tuple, op_unpack { }), "");
+    static_assert(my_tuple.unpack(op_unpack { }), "");
+
+    static_assert(decltype(at(my_tuple, index0))::value == false, "");
+    static_assert(decltype(at(my_tuple, index1))::value == 5, "");
+    static_assert(decltype(my_tuple.at(index0))::value == false, "");
+    static_assert(decltype(my_tuple.at(index1))::value == 5, "");
+
+    constexpr auto transformed = my_tuple.transform(op_transform { });
+    using transformed_type     = clean_type<decltype(transformed)>;
+    using transformed_expected = basic_tuple<Wrapper<c_bool_t<false>>, Wrapper<c_size_t<5>>>;
+
+    static_assert(is_same<transformed_type, transformed_expected>::value, "");
+}
\ No newline at end of file
diff --git a/test/mp/intern/has_value.cpp b/test/mp/intern/has_value.cpp
index 40b30ef..ea09ff6 100644
--- a/test/mp/intern/has_value.cpp
+++ b/test/mp/intern/has_value.cpp
@@ -5,6 +5,6 @@ using namespace ::utl::mp::intern;
 
 namespace test_mp_intern_has_value
 {
-    static_assert( has_value<c_true>::value, "");
+    static_assert( has_value<c_true_t>::value, "");
     static_assert(!has_value<bool>::value, "");
 }
\ No newline at end of file
diff --git a/test/mp/util/default.cpp b/test/mp/misc/default.cpp
similarity index 79%
rename from test/mp/util/default.cpp
rename to test/mp/misc/default.cpp
index 1f5d397..5ceec7c 100644
--- a/test/mp/util/default.cpp
+++ b/test/mp/misc/default.cpp
@@ -1,4 +1,4 @@
-#include <cpputils/mp/util/default.h>
+#include <cpputils/mp/misc/default.h>
 
 namespace test_mp_util_default
 {
diff --git a/test/mp/util/is_a.cpp b/test/mp/misc/is_a.cpp
similarity index 63%
rename from test/mp/util/is_a.cpp
rename to test/mp/misc/is_a.cpp
index 1734ac8..7ec0f8b 100644
--- a/test/mp/util/is_a.cpp
+++ b/test/mp/misc/is_a.cpp
@@ -1,6 +1,6 @@
 #include <cstdint>
 #include <cpputils/mp/core/const.h>
-#include <cpputils/mp/util/is_a.h>
+#include <cpputils/mp/misc/is_a.h>
 
 namespace test_mp_util_is_a
 {
@@ -14,5 +14,5 @@ using namespace ::test_mp_util_is_a;
 
 static_assert( is_a<int, tagged_int>, "is_a");
 static_assert(!is_a<int, tagged_float>, "is_a");
-static_assert( is_a<tag_const<int>>(integral_constant<int, 1> { }), "is_a");
-static_assert(!is_a<tag_const<int>>(integral_constant<uint8_t, 1> { }), "is_a");
\ No newline at end of file
+static_assert( is_a<tag_integral_constant<int>>(integral_constant<int, 1> { }), "is_a");
+static_assert(!is_a<tag_integral_constant<int>>(integral_constant<uint8_t, 1> { }), "is_a");
\ No newline at end of file
diff --git a/test/mp/util/make.cpp b/test/mp/misc/make.cpp
similarity index 79%
rename from test/mp/util/make.cpp
rename to test/mp/misc/make.cpp
index f865c59..932da8b 100644
--- a/test/mp/util/make.cpp
+++ b/test/mp/misc/make.cpp
@@ -1,5 +1,5 @@
 #include <gtest/gtest.h>
-#include <cpputils/mp/util/make.h>
+#include <cpputils/mp/misc/make.h>
 
 using namespace ::utl::mp;
 
diff --git a/test/mp/util/tag_of.cpp b/test/mp/misc/tag_of.cpp
similarity index 88%
rename from test/mp/util/tag_of.cpp
rename to test/mp/misc/tag_of.cpp
index 4c05099..8f31fd2 100644
--- a/test/mp/util/tag_of.cpp
+++ b/test/mp/misc/tag_of.cpp
@@ -1,4 +1,4 @@
-#include <cpputils/mp/util/tag_of.h>
+#include <cpputils/mp/misc/tag_of.h>
 
 namespace test_mp_util_tag_of
 {
diff --git a/test/mp/util/to.cpp b/test/mp/misc/to.cpp
similarity index 98%
rename from test/mp/util/to.cpp
rename to test/mp/misc/to.cpp
index 26055a2..f1dacb6 100644
--- a/test/mp/util/to.cpp
+++ b/test/mp/misc/to.cpp
@@ -1,5 +1,5 @@
 #include <gtest/gtest.h>
-#include <cpputils/mp/util/to.h>
+#include <cpputils/mp/misc/to.h>
 
 using namespace ::utl::mp;
 
diff --git a/test/mp/operations/logical/and.cpp b/test/mp/operations/logical/and.cpp
new file mode 100644
index 0000000..b3a7c51
--- /dev/null
+++ b/test/mp/operations/logical/and.cpp
@@ -0,0 +1,9 @@
+#include <cpputils/mp/operations/logical/and.h>
+
+using namespace ::utl::mp;
+
+namespace test_mp_operations_logical_and
+{
+    static_assert( and_(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1), "");
+    static_assert(!and_(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1), "");
+}
\ No newline at end of file
diff --git a/test/mp/operations/logical/or.cpp b/test/mp/operations/logical/or.cpp
new file mode 100644
index 0000000..99ab183
--- /dev/null
+++ b/test/mp/operations/logical/or.cpp
@@ -0,0 +1,9 @@
+#include <cpputils/mp/operations/logical/or.h>
+
+using namespace ::utl::mp;
+
+namespace test_mp_operations_logical_or
+{
+    static_assert(!or_(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), "");
+    static_assert( or_(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), "");
+}
\ No newline at end of file
diff --git a/test/mp/operations/value.cpp b/test/mp/operations/value.cpp
new file mode 100644
index 0000000..8018a7c
--- /dev/null
+++ b/test/mp/operations/value.cpp
@@ -0,0 +1,9 @@
+#include <cpputils/mp/operations/value.h>
+
+using namespace ::utl::mp;
+
+namespace test_mp_operations_value
+{
+    constexpr integral_constant<int, 6> my_const{ };
+    static_assert(value(my_const) == 6, "");
+}
\ No newline at end of file