Concept Lite (Filip Roséen)

concept_lite.cpp

#include <type_traits>

template <class T, class = std::enable_if_t<std::is_integral<T>::value>>
using integral_t = T;

// the usage
template <class T>
void f(integral_t<T> a) {}

int main()
{
    f (  123); // ok
//  f (3.14f); // ill-formed
}

One must be aware of the fact that the above technique will make it troublesome to provide an additional overload of f having the same signature — since we, effectively, are declaring template<class T> void f (T) in both cases.

Reference:
https://b.atch.se/posts/constexpr-meta-container

Works fine as variadic argument too.