commonmark-hs style attributes?

[not-my-profile]

The commonmark-hs library used by pandoc has a very nice attributes extension that allows attributes to be attached to any inline or block elements, e.g:

{.test}
* foo
* bar

attaches the attribute class=test to the list and *test*{#ident} results in <em id="ident">hi</em>.

How difficult would it be to implement the same for Marko?