> and get back a tree-like
structure composed of hashes (sequence), arrays (repetition) and strings (like
we had initially).</p>
<p>Once you start naming things, you&#8217;ll notice that what you don&#8217;t name,
disappears. Parslet assumes that <em>what you don&#8217;t name is unimportant</em>.</p>
<pre class="sh_ruby"><code title="inline_parser"> 
parser =  str('a').as(:a) &gt;&gt; str(' ').maybe &gt;&gt; 
          str('+').as(:o) &gt;&gt; str(' ').maybe &gt;&gt; 
          str('b').as(:b)
parser.parse(