title: Get elements of list beginning with specific letter
body: <p>I have a list of words <code>allWords</code> and I am trying to create a new list from <code>allWords</code> containing only those words that begin with a specific letter <code>currLetter</code>.  Looking at the docs, <code>collection.map()</code> seems like a great choice. However the statement below won't compile since <code>.starts(with: )</code> returns a boolean.</p>
  <pre><code>targetWords = allWords.map { $0.starts(with: currLetter) }
  </code></pre>
  <p>Can anyone point me in the right direction?</p>