title: Making sense of forall and exists output on empty list
body: <pre><code>scala&gt; val l = List()
  l: List[Nothing] = List()
  
  scala&gt; l.forall(x=&gt;false)
  res0: Boolean = true
  
  scala&gt; l.forall(x=&gt;true)
  res1: Boolean = true
  
  scala&gt; l.exists(x=&gt;false)
  res2: Boolean = false
  
  scala&gt; l.exists(x=&gt;true)
  res3: Boolean = false
  </code></pre>
  
  <p>For above 2 predicate, now that no element exists in the list, how come forall return true? I am confused. could you somebody help explain?</p>