My preferred solution looks like: (published 2021-02-26) The program will get a list of two atoms, “published”, and “2021-02-26”. It can complain if you’ve

My preferred solution looks like: (published 2021-02-26) The program will get a list of two atoms, “published”, and “2021-02-26”. It can complain if you’ve eg written “published” when you should have written “submission_date” and it can complain if the next atom isn’t a valid date. You don’t need to tell the reader to parse something as a date because the reader isn’t best placed to know what should and shouldn’t be a date. Whereas the program should know exactly where it expects dates to be so it might as well handle parsing them so you don’t need to tag dates when you write your config. Any human can read that date and know what it means so why bother tagging it if the machine can also know it should be a date.