title: How do you copy between arrays of different sizes in Rust?
body: <p>If I have two arrays of different sizes:</p>
  
  <pre><code>let mut array1 = [0; 8];
  let array2 = [1, 2, 3, 4];
  </code></pre>
  
  <p>How would I copy <code>array2</code> into the first 4 bytes of <code>array1</code>?  I can take a mutable 4 byte slice of array1, but I'm not sure how or if I can assign into it.</p>