title: Swift error cannot invoke '+' with an argument list of type '($T28, $T32)'
body: <p>I'm getting a strange error that I can't help but think is a compiler error. In Swift, in either a Playground or in an iOS app, if I do the following...</p>
  
  <pre><code>let array = [0, 1, 2, 3, 4, 5]
  let sum = array[0] + array[1] + array[2] + array[3] + array[4] + array[5]
  </code></pre>
  
  <p>...I get the following compiler error.</p>
  
  <pre><code>cannot invoke '+' with an argument list of type '($T28, $T32)'
  </code></pre>
  
  <p>Just for grins, I changed that to an array of strings and I get the same. However, if I just add the first five values, no error. Leaving aside the fact that this is not the best way to sum up these numbers, how is this not a compiler error?</p>
  
  <p>And if it isn't a compiler error, why isn't it?</p>