Thanks Paul, this is just before the v1.5.0 release, so the timing is also positive.
I believe we have made many decisions along the way that moved us considerably away from Calendrical Calculations, especially in supporting only year-month-day / hour-min-sec calendars and the rata die representation itself. Given the information above and the fact our "rata die" is no longer the "by the book" definition, I believe we should change the name to something more independent. *José Valim* www.plataformatec.com.br Skype: jv.ptec Founder and Director of R&D On Fri, Jul 14, 2017 at 1:17 AM, Paul Schoenfelder < [email protected]> wrote: > Hey all, > > So I'm concerned about something I've noticed recently. I've seen multiple > mentions of this book (Calendrical Calculations by Reingold and Dershowitz) > and use of it's algorithms in Elixir's Calendar implementation, and I know > I mentioned it back when I first suggested the idea of using something like > the "rata die" concept to support multiple calendars. The problem is that > the code and algorithms in the book are restrictively licensed. I wrote to > Professor Reingold early last year (May-ish) about using the ideas from the > book in Timex to implement support for multiple calendars as well as > implement some of the alternate calendars, particularly the lunar ones. I > heard back from Professor Dershowitz fairly quickly, and the gist was that > I was free to use it for anything non-commercial, as long as it was > appropriately attributed and restricted to non-commercial use. Because of > this, I chose to avoid using it's contents as an implementation reference > in Timex because it is used in commercial software. Below is the reply I > received from him: > > Dear Paul, >> > > > >> Thank you for your generous thanks. >> Feel free to use our programs for your free (noncommercial) use, >> provided proper attribution is given to Calendrical Calculations. >> Please send us a link when you do publish anything. >> But if you distribute it, it must preserve the attribution and >> restriction to non-commercial usage. >> > > > Best, >> Nachum >> > > Recently in some PRs I happened to read through, I saw mention that the > contributor was implementing the code using the algorithms from Calendrical > Calculations. I think that could represent a real issue - Elixir is used in > commercial software, and it seems to me like this could open up the > language (or worse, the authors) to some kind of legal trouble. > > I haven't been reading calendar-related PRs in depth for some time now > because I've been pretty busy, so I don't know how much we've leaned on the > book in Elixir. The use of the "rata die" concept is probably less > troublesome since it's implementation is very different depending on what > date you choose for the conversion, but if we've followed the algorithm > from the book 1:1, then I think we'll have to change it. > > I apologize for not bringing this up sooner, it didn't occur to me until > today the ramifications - up until now I had just assumed we were using it > as an authoritative reference on how to build calendar code, rather than > using it as a source reference. > > If I'm mistaken about how we've been using it, awesome! I just want to > make sure we're in the clear :) > > Paul > > > -- > You received this message because you are subscribed to the Google Groups > "elixir-lang-core" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit https://groups.google.com/d/ > msgid/elixir-lang-core/CAK%3D%2B-Ts6_wH6R_yUL-Uur- > rrjQ20E9DmnZji7Y9NP1fDTvRYKA%40mail.gmail.com > <https://groups.google.com/d/msgid/elixir-lang-core/CAK%3D%2B-Ts6_wH6R_yUL-Uur-rrjQ20E9DmnZji7Y9NP1fDTvRYKA%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4JntWiML5-ZhFT%2BF0bjMqvUDkNnfA3nA41QzwZxjB7bDw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
