Argggh! Seeing “tell—tale sign” when it should be “tell-tale sign” is even worse! The point isn't to use punctuation, it's to use punctuation properly!
Blot out, correct, insert, refine,
Enlarge, diminish, interline;
Be mindful, when Invention fails;
To scratch your Head, and bite your Nails.
Your poem finish'd, next your Care
Is needful, to transcribe it fair.
In modern Wit all printed Trash, is
Set off with num'rous Breaks⸺and Dashes—
When I was growing up, I saw plays also use it like this:
The two are in a room.
-- Some guy says this
-- The other guy says that
I believe I've also seen it in Spanish and Portuguese.
Related and perhaps interesting: https://mathstodon.xyz/@mjd/114730157688607856