title: String array reduce
body: <p>I am trying to join the elements of a String array via the reduce function. A tried for a bit now, but I can't get what the problem exactly is. This is what I believe should do the trick. I have tried other alternatives too, but given the huge amount I will wait for some input:</p>
  
  <pre><code>var genres = ["towel", "42"]
  var jointGenres : String = genres.reduce(0, combine: { $0 + "," + $1 })
  </code></pre>
  
  <p>Error:</p>
  
  <blockquote>
    <p>..:14:44: Cannot invoke '+' with an argument list of type
    '(IntegerLiteralConvertible, combine: (($T6, ($T6, $T7) -> ($T6, $T7)
    -> $T5) -> ($T6, ($T6, $T7) -> $T5) -> $T5, (($T6, $T7) -> ($T6, $T7) -> $T5, $T7) -> (($T6, $T7) -> $T5, $T7) -> $T5) -> (($T6, ($T6, $T7) -> $T5) -> $T5, (($T6, $T7) -> $T5, $T7) -> $T5) -> $T5)'</p>
  </blockquote>
  
  <p>From my understanding, $0 should be inferred as a String and $1, by combination with $0, should result as a String too. I don't know what's the deal with the type system here. Any idea?</p>