title: Why does str primarily exist in it's borrowed form?
body: <p>This is how the <code>str</code> type is used:</p>
  
  <pre><code>let hello = "Hello, world!";
  
  // with an explicit type annotation
  let hello: &amp;'static str = "Hello, world!";
  </code></pre>
  
  <p><code>let hello: str = "Hello, world!";</code> leads to <code>expected `str`, found `&amp;str`</code></p>
  
  <p>Why is the default type of the text not just <code>str</code> unlike all primitive types, vectors, and <code>String</code>? Why is it a reference?</p>