title: Why is there not 'Alternative' instance for 'Control.Applicative.Const'
body: <p>There is an instance <code>Monoid a =&gt; Monoid (Const a b)</code> for the <a href="http://hackage.haskell.org/package/base-4.7.0.2/docs/Control-Applicative.html#t:Const" rel="nofollow"><code>Const</code></a> functor from <code>Control.Applicative</code>. There is also an instance <code>Monoid m =&gt; Applicative (Const m)</code>. </p>
  
  <p>I would therefore expect that there is also an instance <code>Monoid m =&gt; Alternative (Const m)</code> that coincides with the one for <code>Monoid</code>. Is this just an omission that should be fixed, or is there a deeper reason?</p>