title: What's the difference between `1L` and `1`?
body: <p>I often seen the symbol <code>1L</code> (or <code>2L</code>, <code>3L</code>, etc) appear in R code.  Whats the difference between <code>1L</code> and <code>1</code>?  <code>1==1L</code> evaluates to <code>TRUE</code>.   Why is <code>1L</code> used in R code?</p>