What it's like building a real website in Node.js(travisglines.com)

  foo(..., function (n) {
     // closure over q, r, s
  });

  function bar(q, r, s) {
    return function(n) {
      // still has dependency on q, r, s
    }
  }

  foo(..., bar(q, r, s));

  function onServerRequest(req, res) {
      db.query("get filename", function(result) {
          fs.readContents(result, function (data) {
              res.write(data);
          });
      });
  }

  function onServerRequest(req, res) {
      var queryPromise = db.queryPromise("get filename");
      var filename = yield queryPromise;

      var data = yield db.readContentsPromise(filename);
    
      res.write(data);
  }

  function queryPromise(query) {
      var promise = new Promise();
      db.query(query, function(result) {
          promise.putValue(result);
      });
      return promise;
  }