{% for category in categories %}
    {% set postCount = category.post_count %}
    <li {% if category.slug == currentCategorySlug %}class="active"{% endif %}>
        <a href="{{ category.url }}">{{ category.name }}</a> 
        {% if postCount %}
            <span class="badge">{{ postCount }}</span>
        {% endif %}

        {% if category.children|length > 0 %}
            <ul>
                {% partial __SELF__ ~ "::items"
                    categories=category.children
                    currentCategorySlug=currentCategorySlug
                %}
            </ul>
        {% endif %}
    </li>
{% endfor %}