Hello gentle Haskell folks,<div><br></div><div>I happened to read &quot;Beautiful code&quot;&#39;s chapter 1 today and found Brian Kerninghan&#39;s regex implementation. In it he only shows the * meta character. I can easily understand how + can be built but am having trouble with building ? (zero or one). I&#39;d really appreciate it if some one could help me understand it.</div>
<div><br></div><div>Regards,</div><div>Kashyap</div>