To my surprise, I find than acceptable (though not as good as when) in
- Hardly had he come home than it started to rain.
It's terrible without the negative preposing, though:
- *He had hardly come home than it started to rain
which makes me suspect this is a phenomenon of negation.
After all, aside from the fact that hardly, barely, scarcely, and rarely are all negative triggers themselves, baseline comparison clauses in comparatives (the clauses that begin with than) are also negative environments, as the NPI ever below shows.
- He got wetter than he ever expected on the walk home.
EDIT
In retrospect, I think
- Hardly had he come home than it started to rain.
is acceptable because hardly is a mimic of the common idiom no sooner
- No sooner had he come home than it started to rain.
which is both negative and comparative, therefore licensing than. Hardly is somewhat negative, as noted, but not comparative; no sooner is both.
To the extent that hardly had he sounds like no sooner had he, it works.
Of course, mimicry is very much a YMMV phenomenon.
I see your point, but it is true that I did not mix them up because I have seen them in aforementioned dictionaries as observed here:
link link
Sincere, OP
– Mister Obamium Aug 30 '21 at 10:27