title: do section in lambda notation - for mapM_ function
body: <p>How to use <code>do</code> notation in lambda expression in <code>mapM_</code> ?   </p>
  
  <pre><code>mapM_ (\x -&gt; do let x = someComputation, return ())
  </code></pre>
  
  <p>In real, I am searching for something like this comma.</p>