title: Haskell intersect two lists and remove double elements
body: <p>I'm new to Haskell and need an function to intersect two lists, but remove double elements.</p>
  
  <p>If I load the Data.List </p>
  
  <pre><code>import Data.List
  </code></pre>
  
  <p>I can use this function:</p>
  
  <pre><code>intersect "abbcd" "abbe"
  "abb"
  </code></pre>
  
  <p>The outcome is "abb", but what I need is:</p>
  
  <pre><code>   intersectFunction "abbcd" "abbe"
      "ab"
  </code></pre>
  
  <p>So the double char from the lists should display only once.</p>
  
  <p>Any ideas?</p>