ISO dates (such as 2025-07-28), being as they are a well-known standard in software, have the potential to connect your computing environment. This library aims to provide utilities that makes working with ISO dates in Emacs simple and fun, both for users and developers.
This library offers some commands which let you use ISO dates with several stock Emacs packages:
- iso-date-show-calendar
- iso-date-show-org-agenda
- iso-date-show-diary
- iso-date-send-to-calc
There are also commands to insert or manipulate ISO dates:
- iso-date-insert
- iso-date-at-point-day-up
- iso-date-at-point-day-down
- iso-date-at-point-do-shift
Or display information about them:
- iso-date-echo-difference
- iso-date-pretty-print
The package also offers integration with embark (see this pull request for context). A target for ISO dates is provided (iso-date), and several of the previous commands are bound in embark-iso-date-map. In order to activate it, just add the following to your init file:
(require 'embark-iso-date)This library provides the iso-date function. Without arguments, it returns an ISO date string for current day:
(iso-date)
=> e.g. "2025-07-28"It can also take keywords which modify the date returned.
(iso-date :day +3)
=> e.g. "2025-07-31"Valid keywords are :day, :month and :year. This does not simply manipulates the string; it parses the date, uses decoded-time-add, and then reconverts it to ISO. So you never end up with an invalid date.
iso-date can also take the :start-day keyword, which changes the starting point relative to which modifications are applied.
(iso-date :start-date "2000-12-18" :day +7)
=> "2000-12-25"Apart from this, the library provides other functions which may be useful for packages dealing with ISO dates.
For converting from/back to ISO:
- iso-date-to-calendar
- iso-date-to-calendar-lax
- iso-date-from-calendar
- iso-date-to-internal
- iso-date-from-internal
For validating dates:
- iso-date-valid-p
For extracting values:
- iso-date-year
- iso-date-month
- iso-date-day
Others:
- iso-date-between-dates-p
- iso-date-list-dates-between
Last but not least, this library adds iso-date as a thing recognized by the thingatpt library. The iso-date-at-point and iso-date-bounds functions are provided.
NOTE: iso-date is a high-level library. If you just need to parse an ISO date, use the built-in iso8601 library, or its wrapper time-date.