do-notation is just syntax in theory but in practice<br>
it&#39;s difficult to avoid it. Try to write any OpenGL<br>
program in terms of `&gt;&gt;=`,  `&gt;&gt;` and `return`. <br>
I don&#39;t like to use `do` knowing that it&#39;s just<br>
syntax sugar but sometimes it help a lot. <br><br>