Tightness and looseness of nested lists

Spec
1 
+ Is this wrapping list tight, or loose?
  * This nested list is definitely tight.
  -


  -

In the above example, there’s at least three lists. The outermost +-based one, the definitely-tight *-based one, and the --based list(s).

  • commonmark.js thinks the +-based list is tight. The * list is tight, and the - list is loose (and it stays loose, even if there’s text in one or both items).

  • pulldown-cmark thinks the +-based list is tight, and agrees with commonmark.js on the nested lists, too.

  • commonmark-hs thinks the +-based list is loose, unless there’s text after the first -, at which it becomes tight (the + list remains loose, even when there’s text after the second -)

  • Markdown-it thinks there’s two --based lists. The +-based list is loose, but, like commonmark-hs, becomes tight if text is put after the first -.

  • Goldmark, which I tested by running Hugo, does this:

    <ul>
  <li>
    Is this wrapping list tight, or loose?
    <ul>
      <li>This nested list is definitely tight.</li>
    </ul>
    <ul><li></li></ul>
  </li>
</ul>
<ul>
  <li></li>
</ul>

I’ve also filed an issue at [fuzz result] counterintuitive list tightness · Issue #144 · jgm/commonmark-hs · GitHub