How to sort a hash converted to an array in Liquid

My understanding is that Liquid converts Ruby Hashes to arrays for use in tags. For example, when using Jekyll:

{% for category in site.categories %}
    <li>{{ category[0] }}</li>
{% endfor %}

... converts site.categories to an array of tuples in which [0] refers to the key, [1] the list of values.

If I wanted the above category map to be sorted alphabetically by the key ([0] of each tuple) how can I do this?