title: Type of a heterogeneous list (HList) of values behind a type constructor
body: <p>I want to define a function that takes an arbitrarily sized <a href="https://hackage.haskell.org/package/HList-0.5.0.0" rel="nofollow noreferrer">HList</a> of values behind some type constructor, e.g. <code>Maybe</code>:</p>
  
  <pre class="lang-hs prettyprint-override"><code>foo :: HList '[t a, t b, t c, ...] -&gt; Bar
  -- For example:
  foo :: HList '[Maybe a, Maybe b, Maybe c, ...] -&gt; Bar
  </code></pre>
  
  <p>Is there some way to do that in Haskell? Thanks!</p>