title: Is there a way to make GHC provide the type class constraints of typed holes?
body: <h1>Current behavior</h1>
  
  <pre><code>Prelude&gt; show _
  
  &lt;interactive&gt;:7:6:
      Found hole ‘_’ with type: a0
      Where: ‘a0’ is an ambiguous type variable
      Relevant bindings include it :: String (bound at &lt;interactive&gt;:7:1)
      In the first argument of ‘show’, namely ‘_’
      In the expression: show _
      In an equation for ‘it’: it = show _
  </code></pre>
  
  <h1>Desired behavior</h1>
  
  <p>It would be nice if GHC would also tell me that the typed hole has the <code>Show</code> type class constraint.</p>
  
  <h1>Misc</h1>
  
  <p><em>GHC Version 7.8.1</em></p>