title: createDataFrame() failing, can't figure out why
body: <p>I'm trying to create a dataframe using what seems to be the canonical "hello world" of creating spark dataframes and cannot fathom why its failing. Help!</p>
  
  <pre><code>from pyspark.sql.types import *
  schema = StructType([StructField("product", StringType(), True)])
  l = [('foo')]
  rdd = sc.parallelize(l)
  df = sqlContext.createDataFrame(rdd, schema)
  df.show()
  </code></pre>
  
  <p>Above code throws below error</p>
  
  <pre><code>ValueError: Unexpected tuple 'foo' with StructType`
  </code></pre>
  
  <p>The code is basically lifted straight out of <a href="https://spark.apache.org/docs/1.6.2/api/python/pyspark.sql.html#" rel="nofollow noreferrer">pyspark.sql module</a> so i am completely stumped.</p>