title: How can I update an item in a vector in Clojure?
body: <p>If I have a Vector:</p>
  
  <pre><code>[1 2 3 4 5 6 7 8 9]
  </code></pre>
  
  <p>: and I want to replace the 5 with a 0 to give:</p>
  
  <pre><code>[1 2 3 4 0 6 7 8 9]
  </code></pre>
  
  <p>How can I do this when I only know the index as being 4?</p>
  
  <p>Something like:</p>
  
  <pre><code> (replace-in-vec [1 2 3 4 5 6 7 8 9] 4 0)
  </code></pre>