Install libcalendar-ocaml-dev by entering the following commands in the terminal:
sudo apt update sudo apt install libcalendar-ocaml-dev
Description:
OCaml library providing operations over dates and times (dev files)
OCaml library implementing common date/time operations with timezones and pretty printing support.
Homepage: http://calendar.forge.ocamlcore.org/
Version: 2.04-1build3
Section: universe/libdevel