Can we get the type of a lambda argument?

Question

Using std::function, we can get the type of an argument using the argument_type, second_argument_type etc. typedefs, but I can\'t see

Answer 1

@Luc's answer is great but I just came across a case where I also needed to deal with function pointers:

template
Arg first_argument_helper(Ret(*) (Arg, Rest...));

template
Arg first_argument_helper(Ret(F::*) (Arg, Rest...));

template
Arg first_argument_helper(Ret(F::*) (Arg, Rest...) const);

template 
decltype(first_argument_helper(&F::operator())) first_argument_helper(F);

template 
using first_argument = decltype(first_argument_helper(std::declval()));

This can be used on both functors and function pointers:

void function(float);

struct functor {
    void operator() (int);
};

int main() {
    std::cout << std::is_same, int>::value
              << ", "
              << std::is_same, int>::value 
              << std::endl;
    return 0;

}