From sort_posts(timeline, 'title', 'date') I'd assume that the posts are sorted by title, and if they have the same title, then they are sorted by date. But the code actually sorts them the other way around: first by date, and only for posts on the same date (i.e. with identical timestamp, as date means timestamp) by title.

That’s a sane assumption to make, I added a little reversed() call to account for this.

How about being able to sort some keys reversed, and some not, by prepending reverse_ to the key name? Standard use case is sorting by date and title: you might want to sort by date reversed to get the newest posts first, but by title alphabetically.

Looks like a good solution to me. It would certainly handle what I'd like to do (and more).

@felixfontein done — prepend with - to get a key reversed (same syntax as used in Django). Review welcome.