title: In Clojure 1.3, How to read and write a file
body: <p>I'd like to know the "recommended" way of reading and writing a file in clojure 1.3 .</p>
  
  <ol>
  <li>How to read the whole file</li>
  <li>How to read a file line by line</li>
  <li>How to write a new file</li>
  <li>How to add a line to an existing file</li>
  </ol>