Calendrical Calculations

What Hacker News says

1. oftenwrongMay 2026
   I still have my copy of Learning Perl. Mostly because it represents a milestone in my learning. I have kept and obtained a number of other books simply because they are antiquated, special and/or classics that are interesting to read even if they are not that useful to me, like Codd's relational book, or Calendrical Calculations. I hope the AI is trained on these sorts of books, so that the knowledge can live on in a different way.
   Show morethread
2. JachMay 2025
   Huh, didn't realize that beach didn't like it so strongly. Still, hardly "much maligned"... My impression was that most people enjoyed it, even though it definitely has some weaknesses and could (especially now 15 years later) use a second edition, if for no other reason than to move off CLISP to SBCL. This seems supported by its high reviews on Amazon and GoodReads. (Of course overall I liked it too, and we got the best music video about lisp out of it.) FWIW my own criticisms were largely style-based: too much of it felt like Scheme code rather than Lisp code, even outside of emphasizing/educating about the more primitive features, with lots of things like inner functions, recursion where looping would have IMO been clearer, and so much use of raw car/cdr/caadr/caddr/whatdr instead of more clearly structured structs or classes or just helper functions called intuitive things like get-foo. (The book Calendrical Calculations: The Ultimate Edition uses lists for all its data structures but helpfully creates many functions to both construct and access their parts. e.g. generic dates are a (year month day) list, but the definition and exclusive use of standard-year, standard-month, and standard-day for getting at them would let one refactor it into a class. There are also functions like gregorian-date, julian-date, and egyptian-date that have exactly the same implementation (making a list of the 3 passed params) but serve as 'typed' list constructors, and indeed could be refactored into something that carried along type information without changing other code.)
   Show morethread
3. buescherNov 2022
   In a similar vein, Calendrical Calculations by Reingold and Dershowitz.
   thread
4. xwowsersxOct 2022
   I highly recommend reading Calendrical Calculations, a book by Edward Reingold and Nachum Dershowitz. It is a beautiful combination of computer science and calendar systems. Also, the Hebrew calendar truly is a marvel, as the book goes through.
   thread
5. a3nMay 2019
   > And the computer doesn't duplicate the proximity once found in the physical card catalog.

   This is what I miss about technical bookstores. Serendipity. And computers can't yet duplicate that, since what is serendipitous often has nothing to do with me until I find it.

   I found Calendrical Calculations on the shelf at SoftPro books in Centennial, while just generally browsing. I have never before, and never since, bought a book about calendar systems. What I like most about it was the historical treatment of different calendar systems and definitions of "day." https://duckduckgo.com/?q=calendrical+calculations&t=lm&ia=p...

   Had I bought it at Amazon, I'd see all sorts of time and calendar books that I have no interest in. But, I never would have found it to begin with.

   Show morethread
6. tzsMay 2017
   "Easter is a feast, not a planet." --Johannes Kepler

   A good reference for anyone who has to write calendar related code is the book "Calendrical Calculations" by Dershowitz and Reingold [1].

   [1] https://www.amazon.com/Calendrical-Calculations-Nachum-Dersh...

   thread