title: Hiding instance declaration from Prelude
body: <p>I am playing with Monoids now and wanted to define my instances of <code>&lt;&gt;</code> and <code>mempty</code> for a list. I wrote this:</p>
  
  <pre><code>instance Semigroup [a] where
    (&lt;&gt;) = (++)
  
  instance Monoid [a] where
    mempty = []
  </code></pre>
  
  <p>But got an error:</p>
  
  <pre><code>Duplicate instance declarations:
       instance Monoid [a] -- Defined at newtype.hs:25:10
       instance Monoid [a] -- Defined in ‘GHC.Base’
  </code></pre>
  
  <p>Probably, I need to add this at the beginning of file:</p>
  
  <pre><code>import Prelude hiding (???)
  </code></pre>
  
  <p>What should I write in place of "???"?</p>