title: Haskell - Capitalize all letters in a list [String] with toUpper
body: <p>I have a list [String] the task ist to remove those elements in the list, which have "q" or "p" and then capitalize all letters in the list with toUpper.</p>
  
  <p>What I tried yet is as follow:</p>
  
  <pre><code>delAndUpper :: [String] -&gt; [String]
  delAndUpper myList = filter (\x -&gt; not('p' `elem` x || 'q' `elem` x)) myList
  </code></pre>
  
  <p>It removes the unwanted elements from the list properly, however I can't apply toUpper on this list since the type of toUpper is Char.</p>
  
  <p>I tried it with map and it does not work.</p>
  
  <pre><code>delAndUpper myList = map toUpper (filter (\x -&gt; not('p' `elem` x || 'q' `elem` x)) myList)
  </code></pre>
  
  <p>I know, that toUpper in this line of code gets a list as value and therefore it can't work, but know how to go a level down into the list and the apply map toUpper.</p>
  
  <p>Could you please help me.</p>
  
  <p>Thanks in advance!</p>
  
  <p>Greetings</p>