Haskell - Reverse polish notation regular expression to expression tree
<p>Im struggling with coming up with algorithm that converts a regular expression (in context of regular languages, there are only 3 operations '.' for concat, '+' for "or" and '*' for iteration) in reverse polish notation to the regular expression tree.</p>

<p>For example i have a regular expression</p>

<pre><code>aa.bb.+
</code></pre>

<p>for which i need to construct following expression tree</p>

<pre><code>      +
    /   \
   .     .
  / \   / \
 b   b a   a  
</code></pre>

<p>Would appreciate any help. Thanks!</p>