hhandoko

    result = success(comment_params)
             ~>> fn p  -> link_reply_to_id(p)  end
             ~>> fn p  -> create_changeset(p)  end
             ~>> fn cs -> assert_changeset(cs) end
             ~>> fn cs -> insert_changeset(cs) end

    (for {
      user   <- currentUser(...)
      group  <- groups.fetchForUser(...)
      friend <- friendships.fetchFriend(...)
      member <- groups.addMember(...)
    } yield {
      render(...)
    }).recover {
      case e: Exception -> ...
    }

    scala> val list = 1 :: 2 :: Nil
    list: List[Int] = List(1, 2)


    scala> val x = list match {
         |   case head :: _ => head
         |   case _         => 0
         | }
    x: Int = 1

    scala> val seq = 1 +: Seq(2, 3) :+ 4
    seq: Seq[Int] = List(1, 2, 3, 4)

    scala> val y = seq match {
         |   case a +: _ :+ b => a + b
         |   case _           => 0
         | }
    y: Int = 5

    val aFuture = future(a)
    val bFuture = future(b)

    (for {
      a <- aFuture
      b <- bFuture
      c <- futureC(a, b)
    } yield c)