A port of the standard implementation, for Chibi Scheme.
All of SRFI19 should work. There are tests to cover the important bits.
If you find a problem, pull requests with failing tests or - even better! - fixes are greatly appreciated.
The standard implementation of SRFI19 was taken from the link in SRFI19. Many thanks to Will Fitzgerald, the author of SRFI19, for providing that.
The implementation file - srfi19.scm - is now wrapped in a Scheme library definition in the srfi19.sld file.
I've added a cond-expand at the top of the implementation file, added Chibi-specific code there, and moved some of the standard implementation into the else block of that cond-expand. Other scheme implementations should be able to add their own implementation code to the same cond-expand.
I've also ported the tests to (chibi test) so they can be run automatically on installation to verify everything is OK. I've added some more tests too.
I've added two new format directives that I'd really rather were better supported everywhere.
~g- day of month. It just outputs the day of the month (1...31). The other two standard directives both specify either blank padding or zero padding but there's no option for no padding.~u- day ordinal suffix. Outputs the locale-specific suffix for the day of the month. For example "rd" for 3, "th" for 6, or "st" for 21. This allows you to format dates as "Sunday, 1st of January 2017". It's possible to insert the "st" in such a format string manually but it doesn't seem a clean approach.