Alphabetical vendor categorization

gistfile1.txt

<ul>
{% assign current = "" %}
{% for product_vendor in shop.vendors %}
{% assign first_letter = product_vendor | strip_html | upcase | truncate: 1, '' %}
    {% unless first_letter == current %}
        <li class="vendor-letter">{{ first_letter }}</li>
    {% endunless %}
    <li>{{ product_vendor | link_to_vendor  }}</li>
    {% assign current = first_letter %}
{% endfor %}
</ul>