title: What does this syntax mean in Haskell: ([]:_)
body: <p>I saw this at a function ([]:_)</p>
  
  <p>Cannot find a definition of it (Google doesn't work well with symbols). So what is it anyway?</p>
  
  <pre><code>type Mat a = [[a]]
  
  myTranspose :: Mat a -&gt; Mat a
  myTranspose ([]:_) = []
  myTranspose p = (map head p) : myTranspose (map tail p)
  </code></pre>