title: Why are parentheses required for array indexing in postgres?
body: <p>In (postgres) SQL, this is valid syntax,</p>
  
  <pre><code>select (array[ [1,2,3], [4,5,6]])[1];
  </code></pre>
  
  <p>but not:</p>
  
  <pre><code>select array[ [1,2,3], [4,5,6]][1];
  </code></pre>
  
  <p>... which is a little surprising to me. What's going on here?</p>