Pipe & Stages with varying task types

gistfile1.cpp

#include <iostream>
#include <type_traits>

template<typename IN, typename OUT = IN>
struct node {
	using in_type = IN;
	using out_type = OUT;
};

template<class A, class...>
struct valid_stage_types : std::true_type {};

template<class A, class B, class... Bs>
struct valid_stage_types<A*, B*, Bs...> : std::integral_constant<bool, std::is_same<typename A::out_type, typename B::in_type>{} && valid_stage_types<B*, Bs...>{}> {};

class pipe {
public:
	template<typename... STAGES>
	pipe(STAGES ... stages) {
		static_assert(valid_stage_types<STAGES...>{}, "Input & output types of the pipe's stages don't match");
		//...
	}
};

int main(int argc, char *argv[]) {
	node<int, char> s1{};
	node<char, std::string> s2{};
	node<std::string, char> s3{};
	pipe(&s1, &s2, &s3);
}