#include <stdio.h>
#include <vector>

template<typename A> struct maybe {
  bool nothing;
  A data;
  maybe(A a) : data(a), nothing(false) { }
  maybe() : nothing(true) { }
  template<typename B> maybe<B> bind (maybe<B> (f)(A)) {
    if (nothing) {
      return maybe();
    } else {
      return maybe(f(data));
    }
  }
};

template<typename A> struct list: std::vector<A> {
  list () : std::vector<A>() { }
  template<int len> list (const A (&a)[len]) : std::vector<A>(a, a + len) { }
  template<typename B> list<B> bind (list<B> (f)(A)) {
    list<B> out;
    for (auto& i : *this) {
      list<B> temp = f(i);
      out.insert(out.end(), temp.begin(), temp.end());
    }
    return out;
  }
};

maybe<int> mprint (int i)
{
  printf("%i\n", i);
  return maybe<int>(i);
}

list<int> lprint (int i)
{
  printf("%i\n", i);
  return list<int>((int[]){i});
}

int main ()
{
  maybe<int> x;
  maybe<int> y = 23;
  x.bind(mprint);
  y.bind(mprint);
  list<int> z = (int[]){1, 2, 3};
  z.bind(lprint);
  return 0;
}