Output list of products types for certain collection

types.liquid

{% if collection %}
<ul>
{% assign typeList = '' %}
<!-- if we have a collection, then we don't need to access it through collections... -->
{% for product in collection.all_products %}
     {% capture type %}{{product.type}}{% endcapture %}
     <!-- using 'unless' instead of 'if () do nothing else do something' -->
     {% unless typeList contains type %}
               <li>{{ product.type | link_to_type }}</li>
               {% capture temp %}{{typeList}}{{product.type}}{% endcapture %}
               {% assign typeList = temp %}
     {% endunless %}
{% endfor %}
</ul>
{% endif %}