gistfile1.cpp

#include <iostream>
#include <type_traits>
using namespace std;

#define ALVIN_SASSERT_IS_SAME(actual, expected) static_assert(std::is_same<actual, expected>::value, "Expected " #expected ", got " #actual ".");

struct Type {};

struct Function {
	template <typename T>
	struct from {
		template <typename U>
		struct to {
			using type = Type;
		};
		using type = to<Type>;
	};
	using type = from<Type>::to<from<Type>::to<Type>>;
};

struct List {
	using type = Function::from<Type>::to<Type>;
	
	template <typename T>
	struct of {
		using type = Type;
	};
};

struct Int {
	using type = Type;
};

template <int i>
struct IntegerLiteral {
	using type = Int;
};

// repeat x = [x] ++ (repeat x)
struct repeat {
	template <typename T>
	using type = typename Function::from<List::of<T>>::template to<List::of<T>>;
	
	template <typename x>
	struct value {
		using type = List::of<typename x::type>;
	};
};

ALVIN_SASSERT_IS_SAME(
	repeat::value<IntegerLiteral<1>>::type,
	List::of<Int>
);

ALVIN_SASSERT_IS_SAME(
	repeat::value<IntegerLiteral<1>>::type,
	List::of<Int>
);

ALVIN_SASSERT_IS_SAME(
	Function::from<Int>::type, 
	Function::from<Type>::to<Type>);

int main(){}