title: What is the Scala syntax for summing a List of objects?
body: <p>For example</p>
  
  <pre><code>case class Blah(security: String, price: Double)
  val myList = List(Blah("a", 2.0), Blah("b", 4.0))
  val sum = myList.sum(_.price) // does not work
  </code></pre>
  
  <p>What is the syntax for obtaining the sum?</p>