Index: uspace/lib/cpp/include/functional
===================================================================
--- uspace/lib/cpp/include/functional	(revision f509d40db8fe17976ac0af8d5719370d40930e3f)
+++ uspace/lib/cpp/include/functional	(revision db54a9d41821389410d5c54b31d1e2db2e8fe804)
@@ -28,4 +28,5 @@
 
 #include <impl/functional.hpp>
+#include <internal/functional/arithmetic_operations.hpp>
 #include <internal/functional/bind.hpp>
 #include <internal/functional/function.hpp>
Index: uspace/lib/cpp/include/impl/functional.hpp
===================================================================
--- uspace/lib/cpp/include/impl/functional.hpp	(revision f509d40db8fe17976ac0af8d5719370d40930e3f)
+++ uspace/lib/cpp/include/impl/functional.hpp	(revision db54a9d41821389410d5c54b31d1e2db2e8fe804)
@@ -50,587 +50,4 @@
 
     /**
-     * 20.9.5, arithmetic operations:
-     */
-
-    template<class T = void>
-    struct plus
-    {
-        constexpr T operator()(const T& lhs, const T& rhs) const
-        {
-            return lhs + rhs;
-        }
-
-        using first_argument_type  = T;
-        using second_argument_type = T;
-        using result_type          = T;
-    };
-
-    template<class T = void>
-    struct minus
-    {
-        constexpr T operator()(const T& lhs, const T& rhs) const
-        {
-            return lhs - rhs;
-        }
-
-        using first_argument_type  = T;
-        using second_argument_type = T;
-        using result_type          = T;
-    };
-
-    template<class T = void>
-    struct multiplies
-    {
-        constexpr T operator()(const T& lhs, const T& rhs) const
-        {
-            return lhs * rhs;
-        }
-
-        using first_argument_type  = T;
-        using second_argument_type = T;
-        using result_type          = T;
-    };
-
-    template<class T = void>
-    struct divides
-    {
-        constexpr T operator()(const T& lhs, const T& rhs) const
-        {
-            return lhs / rhs;
-        }
-
-        using first_argument_type  = T;
-        using second_argument_type = T;
-        using result_type          = T;
-    };
-
-    template<class T = void>
-    struct modulus
-    {
-        constexpr T operator()(const T& lhs, const T& rhs) const
-        {
-            return lhs % rhs;
-        }
-
-        using first_argument_type  = T;
-        using second_argument_type = T;
-        using result_type          = T;
-    };
-
-    template<class T = void>
-    struct negate
-    {
-        constexpr T operator()(const T& x) const
-        {
-            return -x;
-        }
-
-        using argument_type = T;
-        using result_type   = T;
-    };
-
-    namespace aux
-    {
-        /**
-         * Used by some functions like std::set::find to determine
-         * whether a functor is transparent.
-         */
-        struct transparent_t;
-
-        template<class T, class = void>
-        struct is_transparent: false_type
-        { /* DUMMY BODY */ };
-
-        template<class T>
-        struct is_transparent<T, void_t<typename T::is_transparent>>
-            : true_type
-        { /* DUMMY BODY */ };
-
-        template<class T>
-        inline constexpr bool is_transparent_v = is_transparent<T>::value;
-    }
-
-    template<>
-    struct plus<void>
-    {
-        template<class T, class U>
-        constexpr auto operator()(T&& lhs, U&& rhs) const
-            -> decltype(forward<T>(lhs) + forward<U>(rhs))
-        {
-            return forward<T>(lhs) + forward<T>(rhs);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    template<>
-    struct minus<void>
-    {
-        template<class T, class U>
-        constexpr auto operator()(T&& lhs, U&& rhs) const
-            -> decltype(forward<T>(lhs) - forward<U>(rhs))
-        {
-            return forward<T>(lhs) - forward<T>(rhs);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    template<>
-    struct multiplies<void>
-    {
-        template<class T, class U>
-        constexpr auto operator()(T&& lhs, U&& rhs) const
-            -> decltype(forward<T>(lhs) * forward<U>(rhs))
-        {
-            return forward<T>(lhs) * forward<T>(rhs);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    template<>
-    struct divides<void>
-    {
-        template<class T, class U>
-        constexpr auto operator()(T&& lhs, U&& rhs) const
-            -> decltype(forward<T>(lhs) / forward<U>(rhs))
-        {
-            return forward<T>(lhs) / forward<T>(rhs);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    template<>
-    struct modulus<void>
-    {
-        template<class T, class U>
-        constexpr auto operator()(T&& lhs, U&& rhs) const
-            -> decltype(forward<T>(lhs) % forward<U>(rhs))
-        {
-            return forward<T>(lhs) % forward<T>(rhs);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    template<>
-    struct negate<void>
-    {
-        template<class T>
-        constexpr auto operator()(T&& x) const
-            -> decltype(-forward<T>(x))
-        {
-            return -forward<T>(x);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    /**
-     * 20.9.6, comparisons:
-     */
-
-    template<class T = void>
-    struct equal_to
-    {
-        constexpr bool operator()(const T& lhs, const T& rhs) const
-        {
-            return lhs == rhs;
-        }
-
-        using first_argument_type  = T;
-        using second_argument_type = T;
-        using result_type          = bool;
-    };
-
-    template<class T = void>
-    struct not_equal_to
-    {
-        constexpr bool operator()(const T& lhs, const T& rhs) const
-        {
-            return lhs != rhs;
-        }
-
-        using first_argument_type  = T;
-        using second_argument_type = T;
-        using result_type          = bool;
-    };
-
-    template<class T = void>
-    struct greater
-    {
-        constexpr bool operator()(const T& lhs, const T& rhs) const
-        {
-            return lhs > rhs;
-        }
-
-        using first_argument_type  = T;
-        using second_argument_type = T;
-        using result_type          = bool;
-    };
-
-    template<class T = void>
-    struct less
-    {
-        constexpr bool operator()(const T& lhs, const T& rhs) const
-        {
-            return lhs < rhs;
-        }
-
-        using first_argument_type  = T;
-        using second_argument_type = T;
-        using result_type          = bool;
-    };
-
-    template<class T = void>
-    struct greater_equal
-    {
-        constexpr bool operator()(const T& lhs, const T& rhs) const
-        {
-            return lhs >= rhs;
-        }
-
-        using first_argument_type  = T;
-        using second_argument_type = T;
-        using result_type          = bool;
-    };
-
-    template<class T = void>
-    struct less_equal
-    {
-        constexpr bool operator()(const T& lhs, const T& rhs) const
-        {
-            return lhs <= rhs;
-        }
-
-        using first_argument_type  = T;
-        using second_argument_type = T;
-        using result_type          = bool;
-    };
-
-    template<>
-    struct equal_to<void>
-    {
-        template<class T, class U>
-        constexpr auto operator()(T&& lhs, U&& rhs) const
-            -> decltype(forward<T>(lhs) == forward<U>(rhs))
-        {
-            return forward<T>(lhs) == forward<U>(rhs);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    template<>
-    struct not_equal_to<void>
-    {
-        template<class T, class U>
-        constexpr auto operator()(T&& lhs, U&& rhs) const
-            -> decltype(forward<T>(lhs) != forward<U>(rhs))
-        {
-            return forward<T>(lhs) != forward<U>(rhs);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    template<>
-    struct greater<void>
-    {
-        template<class T, class U>
-        constexpr auto operator()(T&& lhs, U&& rhs) const
-            -> decltype(forward<T>(lhs) > forward<U>(rhs))
-        {
-            return forward<T>(lhs) > forward<U>(rhs);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    template<>
-    struct less<void>
-    {
-        template<class T, class U>
-        constexpr auto operator()(T&& lhs, U&& rhs) const
-            -> decltype(forward<T>(lhs) < forward<U>(rhs))
-        {
-            return forward<T>(lhs) < forward<U>(rhs);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    template<>
-    struct greater_equal<void>
-    {
-        template<class T, class U>
-        constexpr auto operator()(T&& lhs, U&& rhs) const
-            -> decltype(forward<T>(lhs) >= forward<U>(rhs))
-        {
-            return forward<T>(lhs) >= forward<U>(rhs);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    template<>
-    struct less_equal<void>
-    {
-        template<class T, class U>
-        constexpr auto operator()(T&& lhs, U&& rhs) const
-            -> decltype(forward<T>(lhs) <= forward<U>(rhs))
-        {
-            return forward<T>(lhs) <= forward<U>(rhs);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    /**
-     * 20.9.7, logical operations:
-     */
-
-    template<class T = void>
-    struct logical_and
-    {
-        constexpr bool operator()(const T& lhs, const T& rhs) const
-        {
-            return lhs && rhs;
-        }
-
-        using first_argument_type  = T;
-        using second_argument_type = T;
-        using result_type          = bool;
-    };
-
-    template<class T = void>
-    struct logical_or
-    {
-        constexpr bool operator()(const T& lhs, const T& rhs) const
-        {
-            return lhs || rhs;
-        }
-
-        using first_argument_type  = T;
-        using second_argument_type = T;
-        using result_type          = bool;
-    };
-
-    template<class T = void>
-    struct logical_not
-    {
-        constexpr bool operator()(const T& x) const
-        {
-            return !x;
-        }
-
-        using argument_type = T;
-        using result_type   = bool;
-    };
-
-    template<>
-    struct logical_and<void>
-    {
-        template<class T, class U>
-        constexpr auto operator()(T&& lhs, U&& rhs) const
-            -> decltype(forward<T>(lhs) && forward<U>(rhs))
-        {
-            return forward<T>(lhs) && forward<U>(rhs);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    template<>
-    struct logical_or<void>
-    {
-        template<class T, class U>
-        constexpr auto operator()(T&& lhs, U&& rhs) const
-            -> decltype(forward<T>(lhs) || forward<U>(rhs))
-        {
-            return forward<T>(lhs) || forward<U>(rhs);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    template<>
-    struct logical_not<void>
-    {
-        template<class T>
-        constexpr auto operator()(T&& x) const
-            -> decltype(!forward<T>(x))
-        {
-            return !forward<T>(x);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    /**
-     * 20.9.8, bitwise operations:
-     */
-
-    template<class T = void>
-    struct bit_and
-    {
-        constexpr T operator()(const T& lhs, const T& rhs) const
-        {
-            return lhs & rhs;
-        }
-
-        using first_argument_type  = T;
-        using second_argument_type = T;
-        using result_type          = T;
-    };
-
-    template<class T = void>
-    struct bit_or
-    {
-        constexpr T operator()(const T& lhs, const T& rhs) const
-        {
-            return lhs | rhs;
-        }
-
-        using first_argument_type  = T;
-        using second_argument_type = T;
-        using result_type          = T;
-    };
-
-    template<class T = void>
-    struct bit_xor
-    {
-        constexpr T operator()(const T& lhs, const T& rhs) const
-        {
-            return lhs ^ rhs;
-        }
-
-        using first_argument_type  = T;
-        using second_argument_type = T;
-        using result_type          = T;
-    };
-
-    template<class T = void>
-    struct bit_not
-    {
-        constexpr bool operator()(const T& x) const
-        {
-            return ~x;
-        }
-
-        using argument_type = T;
-        using result_type   = T;
-    };
-
-    template<>
-    struct bit_and<void>
-    {
-        template<class T, class U>
-        constexpr auto operator()(T&& lhs, U&& rhs) const
-            -> decltype(forward<T>(lhs) & forward<U>(rhs))
-        {
-            return forward<T>(lhs) & forward<U>(rhs);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    template<>
-    struct bit_or<void>
-    {
-        template<class T, class U>
-        constexpr auto operator()(T&& lhs, U&& rhs) const
-            -> decltype(forward<T>(lhs) | forward<U>(rhs))
-        {
-            return forward<T>(lhs) | forward<U>(rhs);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    template<>
-    struct bit_xor<void>
-    {
-        template<class T, class U>
-        constexpr auto operator()(T&& lhs, U&& rhs) const
-            -> decltype(forward<T>(lhs) ^ forward<U>(rhs))
-        {
-            return forward<T>(lhs) ^ forward<U>(rhs);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    template<>
-    struct bit_not<void>
-    {
-        template<class T>
-        constexpr auto operator()(T&& x) const
-            -> decltype(~forward<T>(x))
-        {
-            return ~forward<T>(x);
-        }
-
-        using is_transparent = aux::transparent_t;
-    };
-
-    /**
-     * 20.9.9, negators:
-     */
-
-    template<class Predicate>
-    class unary_negate
-    {
-        public:
-            using result_type   = bool;
-            using argument_type = typename Predicate::argument_type;
-
-            constexpr explicit unary_negate(const Predicate& pred)
-                : pred_{pred}
-            { /* DUMMY BODY */ }
-
-            constexpr result_type operator()(const argument_type& arg)
-            {
-                return !pred_(arg);
-            }
-
-        private:
-            Predicate pred_;
-    };
-
-    template<class Predicate>
-    constexpr unary_negate<Predicate> not1(const Predicate& pred)
-    {
-        return unary_negate<Predicate>{pred};
-    }
-
-    template<class Predicate>
-    class binary_negate
-    {
-        public:
-            using result_type          = bool;
-            using first_argument_type  = typename Predicate::first_argument_type;
-            using second_argument_type = typename Predicate::second_argument_type;
-
-            constexpr explicit binary_negate(const Predicate& pred)
-                : pred_{pred}
-            { /* DUMMY BODY */ }
-
-            constexpr result_type operator()(const first_argument_type& arg1,
-                                             const second_argument_type& arg2)
-            {
-                return !pred_(arg1, arg2);
-            }
-
-        private:
-            Predicate pred_;
-    };
-
-    template<class Predicate>
-    constexpr binary_negate<Predicate> not2(const Predicate& pred);
-
-    /**
      * 20.9.11, member function adaptors:
      */
Index: uspace/lib/cpp/include/internal/functional/arithmetic_operations.hpp
===================================================================
--- uspace/lib/cpp/include/internal/functional/arithmetic_operations.hpp	(revision db54a9d41821389410d5c54b31d1e2db2e8fe804)
+++ uspace/lib/cpp/include/internal/functional/arithmetic_operations.hpp	(revision db54a9d41821389410d5c54b31d1e2db2e8fe804)
@@ -0,0 +1,621 @@
+/*
+ * Copyright (c) 2018 Jaroslav Jindrak
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef LIBCPP_INTERNAL_FUNCTIONAL_ARITHMETIC_OPERATIONS
+#define LIBCPP_INTERNAL_FUNCTIONAL_ARITHMETIC_OPERATIONS
+
+#include <internal/utility/forward_move.hpp>
+#include <type_traits>
+
+namespace std
+{
+    /**
+     * 20.9.5, arithmetic operations:
+     */
+
+    template<class T = void>
+    struct plus
+    {
+        constexpr T operator()(const T& lhs, const T& rhs) const
+        {
+            return lhs + rhs;
+        }
+
+        using first_argument_type  = T;
+        using second_argument_type = T;
+        using result_type          = T;
+    };
+
+    template<class T = void>
+    struct minus
+    {
+        constexpr T operator()(const T& lhs, const T& rhs) const
+        {
+            return lhs - rhs;
+        }
+
+        using first_argument_type  = T;
+        using second_argument_type = T;
+        using result_type          = T;
+    };
+
+    template<class T = void>
+    struct multiplies
+    {
+        constexpr T operator()(const T& lhs, const T& rhs) const
+        {
+            return lhs * rhs;
+        }
+
+        using first_argument_type  = T;
+        using second_argument_type = T;
+        using result_type          = T;
+    };
+
+    template<class T = void>
+    struct divides
+    {
+        constexpr T operator()(const T& lhs, const T& rhs) const
+        {
+            return lhs / rhs;
+        }
+
+        using first_argument_type  = T;
+        using second_argument_type = T;
+        using result_type          = T;
+    };
+
+    template<class T = void>
+    struct modulus
+    {
+        constexpr T operator()(const T& lhs, const T& rhs) const
+        {
+            return lhs % rhs;
+        }
+
+        using first_argument_type  = T;
+        using second_argument_type = T;
+        using result_type          = T;
+    };
+
+    template<class T = void>
+    struct negate
+    {
+        constexpr T operator()(const T& x) const
+        {
+            return -x;
+        }
+
+        using argument_type = T;
+        using result_type   = T;
+    };
+
+    namespace aux
+    {
+        /**
+         * Used by some functions like std::set::find to determine
+         * whether a functor is transparent.
+         */
+        struct transparent_t;
+
+        template<class T, class = void>
+        struct is_transparent: false_type
+        { /* DUMMY BODY */ };
+
+        template<class T>
+        struct is_transparent<T, void_t<typename T::is_transparent>>
+            : true_type
+        { /* DUMMY BODY */ };
+
+        template<class T>
+        inline constexpr bool is_transparent_v = is_transparent<T>::value;
+    }
+
+    template<>
+    struct plus<void>
+    {
+        template<class T, class U>
+        constexpr auto operator()(T&& lhs, U&& rhs) const
+            -> decltype(forward<T>(lhs) + forward<U>(rhs))
+        {
+            return forward<T>(lhs) + forward<T>(rhs);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    template<>
+    struct minus<void>
+    {
+        template<class T, class U>
+        constexpr auto operator()(T&& lhs, U&& rhs) const
+            -> decltype(forward<T>(lhs) - forward<U>(rhs))
+        {
+            return forward<T>(lhs) - forward<T>(rhs);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    template<>
+    struct multiplies<void>
+    {
+        template<class T, class U>
+        constexpr auto operator()(T&& lhs, U&& rhs) const
+            -> decltype(forward<T>(lhs) * forward<U>(rhs))
+        {
+            return forward<T>(lhs) * forward<T>(rhs);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    template<>
+    struct divides<void>
+    {
+        template<class T, class U>
+        constexpr auto operator()(T&& lhs, U&& rhs) const
+            -> decltype(forward<T>(lhs) / forward<U>(rhs))
+        {
+            return forward<T>(lhs) / forward<T>(rhs);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    template<>
+    struct modulus<void>
+    {
+        template<class T, class U>
+        constexpr auto operator()(T&& lhs, U&& rhs) const
+            -> decltype(forward<T>(lhs) % forward<U>(rhs))
+        {
+            return forward<T>(lhs) % forward<T>(rhs);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    template<>
+    struct negate<void>
+    {
+        template<class T>
+        constexpr auto operator()(T&& x) const
+            -> decltype(-forward<T>(x))
+        {
+            return -forward<T>(x);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    /**
+     * 20.9.6, comparisons:
+     */
+
+    template<class T = void>
+    struct equal_to
+    {
+        constexpr bool operator()(const T& lhs, const T& rhs) const
+        {
+            return lhs == rhs;
+        }
+
+        using first_argument_type  = T;
+        using second_argument_type = T;
+        using result_type          = bool;
+    };
+
+    template<class T = void>
+    struct not_equal_to
+    {
+        constexpr bool operator()(const T& lhs, const T& rhs) const
+        {
+            return lhs != rhs;
+        }
+
+        using first_argument_type  = T;
+        using second_argument_type = T;
+        using result_type          = bool;
+    };
+
+    template<class T = void>
+    struct greater
+    {
+        constexpr bool operator()(const T& lhs, const T& rhs) const
+        {
+            return lhs > rhs;
+        }
+
+        using first_argument_type  = T;
+        using second_argument_type = T;
+        using result_type          = bool;
+    };
+
+    template<class T = void>
+    struct less
+    {
+        constexpr bool operator()(const T& lhs, const T& rhs) const
+        {
+            return lhs < rhs;
+        }
+
+        using first_argument_type  = T;
+        using second_argument_type = T;
+        using result_type          = bool;
+    };
+
+    template<class T = void>
+    struct greater_equal
+    {
+        constexpr bool operator()(const T& lhs, const T& rhs) const
+        {
+            return lhs >= rhs;
+        }
+
+        using first_argument_type  = T;
+        using second_argument_type = T;
+        using result_type          = bool;
+    };
+
+    template<class T = void>
+    struct less_equal
+    {
+        constexpr bool operator()(const T& lhs, const T& rhs) const
+        {
+            return lhs <= rhs;
+        }
+
+        using first_argument_type  = T;
+        using second_argument_type = T;
+        using result_type          = bool;
+    };
+
+    template<>
+    struct equal_to<void>
+    {
+        template<class T, class U>
+        constexpr auto operator()(T&& lhs, U&& rhs) const
+            -> decltype(forward<T>(lhs) == forward<U>(rhs))
+        {
+            return forward<T>(lhs) == forward<U>(rhs);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    template<>
+    struct not_equal_to<void>
+    {
+        template<class T, class U>
+        constexpr auto operator()(T&& lhs, U&& rhs) const
+            -> decltype(forward<T>(lhs) != forward<U>(rhs))
+        {
+            return forward<T>(lhs) != forward<U>(rhs);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    template<>
+    struct greater<void>
+    {
+        template<class T, class U>
+        constexpr auto operator()(T&& lhs, U&& rhs) const
+            -> decltype(forward<T>(lhs) > forward<U>(rhs))
+        {
+            return forward<T>(lhs) > forward<U>(rhs);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    template<>
+    struct less<void>
+    {
+        template<class T, class U>
+        constexpr auto operator()(T&& lhs, U&& rhs) const
+            -> decltype(forward<T>(lhs) < forward<U>(rhs))
+        {
+            return forward<T>(lhs) < forward<U>(rhs);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    template<>
+    struct greater_equal<void>
+    {
+        template<class T, class U>
+        constexpr auto operator()(T&& lhs, U&& rhs) const
+            -> decltype(forward<T>(lhs) >= forward<U>(rhs))
+        {
+            return forward<T>(lhs) >= forward<U>(rhs);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    template<>
+    struct less_equal<void>
+    {
+        template<class T, class U>
+        constexpr auto operator()(T&& lhs, U&& rhs) const
+            -> decltype(forward<T>(lhs) <= forward<U>(rhs))
+        {
+            return forward<T>(lhs) <= forward<U>(rhs);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    /**
+     * 20.9.7, logical operations:
+     */
+
+    template<class T = void>
+    struct logical_and
+    {
+        constexpr bool operator()(const T& lhs, const T& rhs) const
+        {
+            return lhs && rhs;
+        }
+
+        using first_argument_type  = T;
+        using second_argument_type = T;
+        using result_type          = bool;
+    };
+
+    template<class T = void>
+    struct logical_or
+    {
+        constexpr bool operator()(const T& lhs, const T& rhs) const
+        {
+            return lhs || rhs;
+        }
+
+        using first_argument_type  = T;
+        using second_argument_type = T;
+        using result_type          = bool;
+    };
+
+    template<class T = void>
+    struct logical_not
+    {
+        constexpr bool operator()(const T& x) const
+        {
+            return !x;
+        }
+
+        using argument_type = T;
+        using result_type   = bool;
+    };
+
+    template<>
+    struct logical_and<void>
+    {
+        template<class T, class U>
+        constexpr auto operator()(T&& lhs, U&& rhs) const
+            -> decltype(forward<T>(lhs) && forward<U>(rhs))
+        {
+            return forward<T>(lhs) && forward<U>(rhs);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    template<>
+    struct logical_or<void>
+    {
+        template<class T, class U>
+        constexpr auto operator()(T&& lhs, U&& rhs) const
+            -> decltype(forward<T>(lhs) || forward<U>(rhs))
+        {
+            return forward<T>(lhs) || forward<U>(rhs);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    template<>
+    struct logical_not<void>
+    {
+        template<class T>
+        constexpr auto operator()(T&& x) const
+            -> decltype(!forward<T>(x))
+        {
+            return !forward<T>(x);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    /**
+     * 20.9.8, bitwise operations:
+     */
+
+    template<class T = void>
+    struct bit_and
+    {
+        constexpr T operator()(const T& lhs, const T& rhs) const
+        {
+            return lhs & rhs;
+        }
+
+        using first_argument_type  = T;
+        using second_argument_type = T;
+        using result_type          = T;
+    };
+
+    template<class T = void>
+    struct bit_or
+    {
+        constexpr T operator()(const T& lhs, const T& rhs) const
+        {
+            return lhs | rhs;
+        }
+
+        using first_argument_type  = T;
+        using second_argument_type = T;
+        using result_type          = T;
+    };
+
+    template<class T = void>
+    struct bit_xor
+    {
+        constexpr T operator()(const T& lhs, const T& rhs) const
+        {
+            return lhs ^ rhs;
+        }
+
+        using first_argument_type  = T;
+        using second_argument_type = T;
+        using result_type          = T;
+    };
+
+    template<class T = void>
+    struct bit_not
+    {
+        constexpr bool operator()(const T& x) const
+        {
+            return ~x;
+        }
+
+        using argument_type = T;
+        using result_type   = T;
+    };
+
+    template<>
+    struct bit_and<void>
+    {
+        template<class T, class U>
+        constexpr auto operator()(T&& lhs, U&& rhs) const
+            -> decltype(forward<T>(lhs) & forward<U>(rhs))
+        {
+            return forward<T>(lhs) & forward<U>(rhs);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    template<>
+    struct bit_or<void>
+    {
+        template<class T, class U>
+        constexpr auto operator()(T&& lhs, U&& rhs) const
+            -> decltype(forward<T>(lhs) | forward<U>(rhs))
+        {
+            return forward<T>(lhs) | forward<U>(rhs);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    template<>
+    struct bit_xor<void>
+    {
+        template<class T, class U>
+        constexpr auto operator()(T&& lhs, U&& rhs) const
+            -> decltype(forward<T>(lhs) ^ forward<U>(rhs))
+        {
+            return forward<T>(lhs) ^ forward<U>(rhs);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    template<>
+    struct bit_not<void>
+    {
+        template<class T>
+        constexpr auto operator()(T&& x) const
+            -> decltype(~forward<T>(x))
+        {
+            return ~forward<T>(x);
+        }
+
+        using is_transparent = aux::transparent_t;
+    };
+
+    /**
+     * 20.9.9, negators:
+     */
+
+    template<class Predicate>
+    class unary_negate
+    {
+        public:
+            using result_type   = bool;
+            using argument_type = typename Predicate::argument_type;
+
+            constexpr explicit unary_negate(const Predicate& pred)
+                : pred_{pred}
+            { /* DUMMY BODY */ }
+
+            constexpr result_type operator()(const argument_type& arg)
+            {
+                return !pred_(arg);
+            }
+
+        private:
+            Predicate pred_;
+    };
+
+    template<class Predicate>
+    constexpr unary_negate<Predicate> not1(const Predicate& pred)
+    {
+        return unary_negate<Predicate>{pred};
+    }
+
+    template<class Predicate>
+    class binary_negate
+    {
+        public:
+            using result_type          = bool;
+            using first_argument_type  = typename Predicate::first_argument_type;
+            using second_argument_type = typename Predicate::second_argument_type;
+
+            constexpr explicit binary_negate(const Predicate& pred)
+                : pred_{pred}
+            { /* DUMMY BODY */ }
+
+            constexpr result_type operator()(const first_argument_type& arg1,
+                                             const second_argument_type& arg2)
+            {
+                return !pred_(arg1, arg2);
+            }
+
+        private:
+            Predicate pred_;
+    };
+
+    template<class Predicate>
+    constexpr binary_negate<Predicate> not2(const Predicate& pred);
+}
+
+#endif