title: Ruby statements, whitespace versus parentheses
body: <h2>Why are parentheses required in this?</h2>
  
  <p>I am looking for a purely syntax related reasoning. This is not a question about what should or not be in ruby for beauty or whatever.</p>
  
  <pre><code>not(['a','u','i','o','e'].include? s[0].downcase)
  #this third line will error!
  not ['a','u','i','o','e'].include? s[0].downcase
  
  #you can also incorrectly represent this as
  not['a','u','i','o','e'].include?(s[0].downcase)
  #but correctly as this with the higher precedence !
  !['a','u','i','o','e'].include?(s[0].downcase)
  #but then again incorrectly as
  !['a','u','i','o','e'].include? s[0].downcase
  </code></pre>
  
  <p>In general I think the whitespaces with (), {}, ;, \n, and end are oddly difficult to get correct in ruby. It has something to do with precendence. Can someone show me a mapping of where and not these invisible () are when executing the above code.</p>