Version 1 of the C++ Extensions for Library Fundamentals provides a number of constexpr variable templates for type traits classes, as well as other similar class templates with public ::value members.
Unless otherwise noted, the following variable templates are defined in the std::experimental namespace.
Type traits
Primary type categories Variable template Value Defined in header
template<classT>constexprboolis_void_v=std::is_void<T>::value;template<classT>constexprboolis_null_pointer_v=std::is_null_pointer<T>::value;template<classT>constexprboolis_integral_v=std::is_integral<T>::value;template<classT>constexprboolis_floating_point_v=std::is_floating_point<T>::value;template<classT>constexprboolis_array_v=std::is_array<T>::value;template<classT>constexprboolis_pointer_v=std::is_pointer<T>::value;template<classT>constexprboolis_lvalue_reference_v=std::is_lvalue_reference<T>::value;template<classT>constexprboolis_rvalue_reference_v=std::is_rvalue_reference<T>::value;template<classT>constexprboolis_member_object_pointer_v=std::is_member_object_pointer<T>::value;template<classT>constexprboolis_member_function_pointer_v=std::is_member_function_pointer<T>::value;template<classT>constexprboolis_enum_v=std::is_enum<T>::value;template<classT>constexprboolis_union_v=std::is_union<T>::value;template<classT>constexprboolis_class_v=std::is_class<T>::value;template<classT>constexprboolis_function_v=std::is_function<T>::value; Composite type categories Variable template Value Defined in header
template<classT>constexprboolis_reference_v=std::is_reference<T>::value;template<classT>constexprboolis_arithmetic_v=std::is_arithmetic<T>::value;template<classT>constexprboolis_fundamental_v=std::is_fundamental<T>::value;template<classT>constexprboolis_object_v=std::is_object<T>::value;template<classT>constexprboolis_scalar_v=std::is_scalar<T>::value;template<classT>constexprboolis_compound_v=std::is_compound<T>::value;template<classT>constexprboolis_member_pointer_v=std::is_member_pointer<T>::value; Type properties Variable template Value Defined in header
template<classT>constexprboolis_const_v=std::is_const<T>::value;template<classT>constexprboolis_volatile_v=std::is_volatile<T>::value;template<classT>constexprboolis_trivial_v=std::is_trivial<T>::value;template<classT>constexprboolis_trivially_copyable_v=std::is_trivially_copyable<T>::value;template<classT>constexprboolis_standard_layout_v=std::is_standard_layout<T>::value;template<classT>constexprboolis_pod_v=std::is_pod<T>::value;template<classT>constexprboolis_literal_type_v=std::is_literal_type<T>::value;template<classT>constexprboolis_empty_v=std::is_empty<T>::value;template<classT>constexprboolis_polymorphic_v=std::is_polymorphic<T>::value;template<classT>constexprboolis_abstract_v=std::is_abstract<T>::value;template<classT>constexprboolis_final_v=std::is_final<T>::value;template<classT>constexprboolis_signed_v=std::is_signed<T>::value;template<classT>constexprboolis_unsigned_v=std::is_unsigned<T>::value; Supported operations Variable template Value Defined in header
template<classT,class...Args>constexprboolis_constructible_v=std::is_constructible<T,Args...>::value;template<classT,class...Args>constexprboolis_trivially_constructible_v=std::is_trivially_constructible<T,Args...>::value;template<classT,class...Args>constexprboolis_nothrow_constructible_v=std::is_nothrow_constructible<T,Args...>::value;template<classT>constexprboolis_default_constructible_v=std::is_default_constructible<T>::value;template<classT>constexprboolis_trivially_default_constructible_v=std::is_trivially_default_constructible<T>::value;template<classT>constexprboolis_nothrow_default_constructible_v=std::is_nothrow_default_constructible<T>::value;template<classT>constexprboolis_copy_constructible_v=std::is_copy_constructible<T>::value;template<classT>constexprboolis_trivially_copy_constructible_v=std::is_trivially_copy_constructible<T>::value;template<classT>constexprboolis_nothrow_copy_constructible_v=std::is_nothrow_copy_constructible<T>::value;template<classT>constexprboolis_move_constructible_v=std::is_move_constructible<T>::value;template<classT>constexprboolis_trivially_move_constructible_v=std::is_trivially_move_constructible<T>::value;template<classT>constexprboolis_nothrow_move_constructible_v=std::is_nothrow_move_constructible<T>::value;template<classT,classU>constexprboolis_assignable_v=std::is_assignable<T,U>::value;template<classT,classU>constexprboolis_trivially_assignable_v=std::is_trivially_assignable<T,U>::value;template<classT,classU>constexprboolis_nothrow_assignable_v=std::is_nothrow_assignable<T,U>::value;template<class T> constexpr bool is_copy_assignable_v =std::is_copy_assignable<T>::value;template<class T> constexpr bool is_trivially_copy_assignable_v =std::is_trivially_copy_assignable<T>::value;template<class T> constexpr bool is_nothrow_copy_assignable_v =std::is_nothrow_copy_assignable<T>::value;template<class T> constexpr bool is_move_assignable_v =std::is_move_assignable<T>::value;template<class T> constexpr bool is_trivially_move_assignable_v =std::is_trivially_move_assignable<T>::value;template<class T> constexpr bool is_nothrow_move_assignable_v =std::is_nothrow_move_assignable<T>::value;template<class T> constexpr bool is_destructible_v =std::is_destructible<T>::value;template<class T> constexpr bool is_trivially_destructible_v =std::is_trivially_destructible<T>::value;template<class T> constexpr bool is_nothrow_destructible_v =std::is_nothrow_destructible<T>::value;template<class T> constexpr bool has_virtual_destructor_v =std::has_virtual_destructor<T>::value; Property queries Variable template Value Defined in header
template<class T> constexpr std::size_t alignment_of_v =std::alignment_of<T>::value;template<class T> constexpr std::size_t rank_v =std::rank<T>::value;template<class T, unsigned I = 0> constexpr std::size_t extent_v =std::extent<T, I>::value; Type relationships Variable template Value Defined in header
template<class T, class U> constexpr bool is_same_v =std::is_same<T, U>::value;template<class Base, class Derived> constexpr bool is_base_of_v =std::is_base_of<Base, Derived>::value;template<class From, class To> constexpr bool is_convertible_v =std::is_convertible<From, To>::value;Other variable templates
comparison Variable template Value Defined in header
template<class R1, class R2> constexpr bool ratio_equal_v =std::ratio_equal<R1, R2>::value;template<class R1, class R2> constexpr bool ratio_not_equal_v =std::ratio_not_equal<R1, R2>::value;template<class R1, class R2> constexpr bool ratio_less_v =std::ratio_less<R1, R2>::value;template<class R1, class R2> constexpr bool ratio_less_equal_v =std::ratio_less_equal<R1, R2>::value;template<class R1, class R2> constexpr bool ratio_greater_v =std::ratio_greater<R1, R2>::value;template<class R1, class R2> constexpr bool ratio_greater_equal_v =std::ratio_greater_equal<R1, R2>::value; Miscellaneous Variable template Value Defined in header
template<class T> constexpr std::size_t tuple_size_v =std::tuple_size<T>::value;Defined in header
template<class Rep> constexpr bool treat_as_floating_point_v =std::chrono::treat_as_floating_point<Rep>::value;[1]Defined in header
template<class T> constexpr bool is_error_code_enum_v =std::is_error_code_enum<T>::value;template<class T> constexpr bool is_error_condition_enum_v =std::is_error_condition_enum<T>::value;Defined in header
template<class T> constexpr bool is_bind_expression_v =std::is_bind_expression<T>::value;template<class T> constexpr int is_placeholder_v =std::is_placeholder<T>::value;Defined in header
template<class T, class Alloc> constexpr bool uses_allocator_v =std::uses_allocator<T, Alloc>::value;Notes
[1]: Defined in the std::chrono::experimental namespace.