title: Is there a Swift equivalent to the 'Filter' function in Python?
body: <p>In python, it is incredibly simple to remove unwanted items from a string/list using the 'filter' function which can be used in conjunction with 'lambda' functions. in python, it's as simple as:</p>
  
  <pre><code>a = "hello 123 bye-bye !!£$%$%"
  b = list(filter(lambda x: x.isalpha(), a))
  c = "".join(b)
  print(c) #Which would print "hellobyebye"
  </code></pre>
  
  <p>Is there any way to easily replicate this in swift without first converting to unicode and then checking if the unicode value is within a certain range? Also, are there any 'lambda' like things in swift?</p>