title: What evaluates to True/False in R?
body: <p>For example, in Ruby, only nil and false are false.  What is what in R?</p>
  
  <p>e.g.: <code>5==TRUE</code> and <code>5==FALSE</code> both evaluate to FALSE.  However, <code>1==TRUE</code> is <code>TRUE</code>. Is there any general rule as to what (objects, numbers, etc.) evaluate to?</p>