title: Typescript: string literal union type from enum
body: <p>I'd like to get a string literal union from an enum.</p>
  
  <p>For this enum…</p>
  
  <pre><code>enum Weekday {
      MONDAY = 'mon',
      TUESDAY = 'tue',
      WEDNESDAY = 'wed'
  }
  </code></pre>
  
  <p>… I'd like to get this:</p>
  
  <pre><code>type WeekdayType = 'mon' | 'tue' | 'wed';
  </code></pre>
  
  <p>I tried <code>typeof keyof Weekday</code> but that resulted in <code>'MONDAY' | 'TUESDAY' | 'WEDNESDAY'</code>. Feel like the solution might have to do with mapped types but I can't seem to wrap my head around it.</p>
  
  <p>How do I do this?</p>