How currying leads to elegant, readable code(fr.umio.us)

    var jp = formatNames2('John', 'Paul');

    var jp = formatNames2('John', 'Paul', _);

    var jp = formatNames2('John', _, 'Jones');

    -- all morally identical
    a ->  b -> c   -> d
    a -> (b -> c   -> d)
    a -> (b -> (c -> d))
    (a, b)  -> c   -> d
    (a, b, c)      -> d
    ((a, b), c)    -> d
    (a, (b, c))    -> d

    flip (someFn :: (a, b, c) -> d)
      :: (b, a, c) -> d
      :: (b, a) -> c -> d
      :: b -> a -> (c -> d)

    var total = reduce(add)(0);  // or 
    var sum = reduce(add)(0)(numbers)

    var total = reduce(add, 0);  // or
    var sum = reduce(add, 0, numbers)

   (defn get-imcomplete-task-summaries [membername]
      (.then (fetch-data)
             (fn [data]
               (sort-by :time
                        (for [task (:tasks data)
                              :when (= membername (:username task))
                              :when (not (:complete task))]
                          task ;; immutable, no need to copy
                          )))))

    getIncompleteTaskSummaries membername =
        fetchData
        >>> tasks
        >>> filter (task => username task == membername and not complete task)
        >>> map (subsetkeys ["id", "dueDate", "title", "priority"])
        >>> sortwithkeyfn getTime

    var getIncompleteTaskSummaries = function(membername) {
        return fetchData().then(function(data) {
          var incompleteTasks = [];
          for (i = 0; i < data.tasks.length; ++i) {
            var task = data.tasks[i];
            if (task.username == membername && !task.complete) {
              incompleteTasks.push({id: task.id, dueDate: task.dueDate, title: task.title, priority: task.priority});
            }
          }
          incompleteTasks.sort(function(a, b) {
            return a.getTime() - b.getTime();
          });
          return incompleteTasks;
        });
      }