pankuzu.erb

<% if breadcrumbs.present? %>
  <ol class="breadcrumbs" vocab="http://schema.org/" typeof="BreadcrumbList">
    <% breadcrumbs.each_with_index do |breadcrumb, i| %>
      <li class="breadcrumb" property="itemListElement" typeof="ListItem">
        <%= link_to breadcrumb.url, itemtype: "http://schema.org/Thing", itemprop: "item" do %>
          <span property="name">
            <%= breadcrumb.name %>
          </span>
          <meta property="position" content="<%= i+1 %>">
        <% end %>
      </li>
    <% end %>
  </ol>
<% end %>

pankuzu.haml

- if breadcrumbs.present?
  %ol.breadcrumbs{typeof: "BreadcrumbList", vocab: "http://schema.org/"}
    - breadcrumbs.each_with_index do |breadcrumb, i|
      %li.breadcrumb{property: "itemListElement", typeof: "ListItem"}
        = link_to breadcrumb.url, itemtype: "http://schema.org/Thing", itemprop: "item" do
          %span{property: "name"}
            = breadcrumb.name
          %meta{content: "#{i+1}", property: "position"}

pankuzu.slim

- if breadcrumbs.present?
  ol.breadcrumbs typeof="BreadcrumbList" vocab="http://schema.org/" 
    - breadcrumbs.each_with_index do |breadcrumb, i|
      li.breadcrumb property="itemListElement" typeof="ListItem" 
        = link_to breadcrumb.url, itemtype: "http://schema.org/Thing", itemprop: "item" do
          span property="name" 
            = breadcrumb.name
          meta content="#{i+1}" property="position"