That's a hyphen, and (to be pedantic) style guides usually do not consider it a dash.
There's also the 2-em dash in some style guides for redacting words, and since care needs to be taken to avoid a line wrap between the em dashes, Unicode has a character for it: ⸺
Finally,
> - em dash: adjoining thought (Hey, so — <declaration>)
This use is sometimes discouraged by style guides, and in many cases, it can be replaced with a colon, comma, or semicolon.
In general, even before AI, the em dash is often considered overused.[0] My guess is that the em dash is perceived as sounding educated, so novice writers who learn about it end up using it recklessly, and LLMs could've picked up this habit from them.
[0]: https://slate.com/human-interest/2011/05/em-dashes-why-write...
I think this is the real reason for its (pre-LLM) ubiquity - it's a really flexible, versatile bit of punctuation, whereas most of its siblings have a more specific meaning or purpose.
A stream of short sentences often feels lazy, reductive, and tedious. But it is more forgiving--you can't fail if you don't try. And it inflates word count, similar to verbose Java vs compact Perl.
The New York Times Manual of Style, for instance, only permits using an en dash as a minus sign. Joining nouns like Sarbanes-Oxley and even number ranges use hyphens instead.
The BBC News Style Guide and the Economist Style Guide similarly use hyphens in place of en dashes - though sometimes BBC seems to use en dashes in place of em dashes.
The University of Cambridge Style Guide simply says to avoid dashes altogether.
The AMA Manual of Style explicitly declares that one should hyphenate two or more nouns of equal importance. They however continue to use the en dash when the first word in the compound modifies more than one word (e.g. anti–Norwalk virus).
The US General Printing Office Style Guide also uses hyphens, so the Sarbanes-Oxley Act is hyphenated in documents published by Congress.
The Chicago Manual of Style nearly got rid of the en dash as well, but backtracked after backlash.
Ceasing the happy tradition of using the hyphen between equal-weighted nouns because of a hacker news comment is the moral equivalent of adopting expletives from the kids menu at a diner.
> The first known documentation of the hyphen is in the grammatical works of Dionysius Thrax. At the time, hyphenation was joining two pieces of text that might otherwise be read as two separate words by a low tie mark. This was necessary due to the ambiguity inherent in the lack of word spacing. In Greek these marks were known as enotikon, officially romanized as a hyphen.
(Not my intent to be pedantic.)
This is not the best source (I’m pressed for time) but it gives a decent explanation: https://editorsmanual.com/articles/en-dash/#elements-of-equa...
While there's no central authority, both Oxford and Cambridge University press style guidelines recommend that.
my favourite (and I hope LLMs never converge to use it)
I checked a message from my last chat with Claude
> Noted for this conversation — though worth flagging
and that's an em-dash (unicode 0x2014)
– Robert Bringhurst, The Elements of Typographic Style
Most of my life, the same has been true about dashes. I use - for every one of the kinds you provided because - lives on my keyboard.
Is there real value in caring? Does it have the same semantic—stripping effect for computers/accessibility devices? The part of me wondering if I really should care is trying to suss out if this is a real problem or just an argument for semantics pedantics.
But I see you using an em-dash to hyphenate "semantic-stripping" as a joke, which is funny. Is that real value? Is conveying to others that you're educated real value?
Konnichiwaー
I've been doing doing it that way for so long I still often use the "--" construct from way back in ascii email days.
At least I've gotten past the two-spaces after a period I learned from the typewriter. Most of the time, anyway.
If you want to be official about things, use the en dash to replace a hyphen in compound adjectives when at least one of the elements is a two-word compound.
the pre–Websterburg Bakery era
n.b. I don't know how to code an endash here. Would love to learn!
Just type it like normal – alt-hyphen on Macs, and I'm sure equivalent on other systems.
I grew up reading novels and plays
Inspector Lestrade and Holmes were speaking:
— What’s up?
— Not much
— Cool.
"I was thinking—"
"Well, there's your first mistake"
But there's also hyphen-minus: https://www.compart.com/en/unicode/U+002D, and a search for 'hyphen' returns a bunch of others: https://www.compart.com/en/unicode/search?q=hyphen.