title: link_to the current page plus/merged with a param
body: <p>A bit of a softball question, but my Google Fu escapes me at the moment.</p>
  
  <p>How do I link to the current page but then specify params to be merged into the query string?</p>
  
  <p>For instance, if the current page is <code>/resources</code>, I want to be able to specify something like <code>current_page_plus(:param =&gt; 'attribute')</code> that evaluates out to <code>/resources?param=attribute</code>. </p>
  
  <p>This would hopefully also merge with existing attributes, so if the current page was <code>/resources?a=b&amp;c=d</code>, then <code>current_page_plus(:c =&gt; 'e')</code> would evaluate to <code>/resources?a=b&amp;c=e</code>.</p>