This library handles dates (YYYY-MM-DD) and periods (in days, months and years). It provides operators on dates and periods. The addition of dates and periods containing months or years is a tricky case that may require roundings. We have taken special care to define those rounding operators and expose different rounding modes for users.

This library is a work in progress. You can find the library's description in lib/dates.mli. There are also a Python and C implementations (which correspond to ports of the OCaml implementation).

The full semantics of the library has been formalized and is available in the related ESOP 2024 paper Formalizing Date Arithmetic and Statically Detecting Ambiguities for the Law.

Just run opam install dates_calc or opam install . if you've cloned the git repository.

The documentation can be built with dune build @doc, and is then available in doc/odoc.html.