Martian Timekeeping in Hare
harelang.org
harelang.org
Not that I know of, no. Hare's concept of timescales is quite unique in itself already.
> Or maybe with at least some solid third-party implementations?
There exist a few libraries and programs out there, but I'm not familiar with all of them.
For simple Martian time (Javascript):
NASA has their graphical "Mars24 Sunclock" (Java):
https://www.giss.nasa.gov/tools/mars24/
As for chronologies, I don't know any other implementations of the Martian Business Calendar. There are implementations of the Darian calendar out there.