title: Spark "sum" command gives Method sum([class java.util.ArrayList]) does not exist
body: <p>Am I going crazy?</p>
  
  <pre><code>from pyspark.sql.functions import *
  sum([2,3,2])
  </code></pre>
  
  <p>Gives:</p>
  
  <pre><code>py4j.Py4JException: Method sum([class java.util.ArrayList]) does not exist
  </code></pre>
  
  <p>How can I just get a simple sum? </p>
  
  <p>What is happening behind the scenes with spark to make things so difficult? </p>