title: type mismatch error involving nested parentheses
body: <p>type mismatch</p>
  <pre><code>found   : ((A, (Long, Array[String], Int))) =&gt; A
  required: (A, (Long, Array[String], Int)) =&gt; A
  </code></pre>
  <p>I don't understand this error I am trying to fold over a sequence where A is the state type. Why has it 'found' a nested tuple where I have provided something like:</p>
  <p><code>xs.foldLeft(zeroSt) {case (st,(a,b,c)) =&gt; st}</code></p>