title: How to type a computed property in the new composition API?
body: <p>Im playing along with the new Vue plugin for using composition API and TypeScript and there is something I'm not quite understanding.</p>
  
  <p>How am I supposed to type computed properties?</p>
  
  <pre><code>import Vue from 'vue'
  import { ref, computed, Ref } from '@vue/composition-api'
  
  export default Vue.extend({
    setup(props, context) {
  
      const movieName:Ref&lt;string&gt; = ref('Relatos Salvajes')
      const country:Ref&lt;string&gt; = ref('Argentina')
  
      const nameAndCountry = computed(() =&gt; `The movie name is ${movieName.value} from ${country.value}`);
  
      return { movieName, country, nameAndCountry }
    }
  })
  </code></pre>
  
  <p>In this simple example I'm declaring two refs and a computed property to join both. VSC is telling me that computed properties are returning <code>ReadOnly</code> type... But I can't make it work.</p>