Expand description
EXSLT date family — https://exslt.org/date/
All functions live in the http://exslt.org/dates-and-times
namespace. The implementation pairs a small hand-written XSD
lexical parser/formatter (sized to the EXSLT 1.0 subset:
dateTime / date / time / duration only) with chrono for the
actual calendar arithmetic — leap years, day-clipping when
adding months, day-of-week computation, etc. Chrono is doing
the work that’s been spec-debugged across millions of users;
we just bridge XSD↔chrono and dispatch by function name.
Functions are defensive: malformed input → empty string (not an error), matching libexslt’s behaviour and the EXSLT spec’s “if the argument is not a valid xs:dateTime, returns an empty string” pattern. Missing-arg-uses-current-time is the other defensive trick the spec uses.