Function join

example/tutorial/introspection.json.cpp:17–19

//! [utilities]
template <typename Xs>
std::string join(Xs&& xs, std::string sep) {
  return hana::fold(hana::intersperse(std::forward<Xs>(xs), sep), "", hana::_ + hana::_);
}

std::string quote(std::string s) { return "\"" + s + "\""; }