solve.cpp

template <class T, class V, class Fn>
vector<V> flat_map(vector<T> elems, Fn trans) {
  vector<V> results;
  for (auto elem: elems) {
    auto inte = trans(elem);
    results.insert(results.end(), inte.begin(), inte.end());
  }
  return results;
}

vector<Result> Board::find(vector<string> strings) {
  return flat_map(strings, [](string s) {
      return vector<Result>();
  });
}

/*
solve.cpp:88:10: error: no matching function for call to 'flat_map'
  return flat_map(strings, [](string s) {
         ^~~~~~~~
solve.cpp:78:11: note: candidate template ignored: couldn't infer template argument 'V'
vector<V> flat_map(vector<T> elems, Fn trans) {
          ^
1 error generated.
*/