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I tested support for the Islamic (Hijri) calendar last year. The tabular variant can be handled at the locale level for the most part. The observed variant, o

I tested support for the Islamic (Hijri) calendar last year. The tabular variant can be handled at the locale level for the most part. The observed variant, on the other hand, is a bit of pain, as it depends on whether someone claims to have seen the new crescent moon (hilal). Since a lot of people depend on Saudi observations, I imagine this will be influential. People grumble about Saudi Arabia, but they set the trends. They're kind of like California that way.

HCIdivision17 10y ago
I had no idea there was that sort of requirement - I guess I had just assumed it was systemized. It sounds fascinating - are there ever conflicts that need to be resolved?
- amerkhalid 10y ago
  All the time. You will see Muslims in a same city celebrating same festival a day apart. I think some serious Muslims get into arguments but most people just enjoy an extra day of festivities.
  - HCIdivision17 10y ago
    I have long held that there aren't any good solutions to the date/time issue (like naming things and cache invalidation :), other than just find some way to hitch to UTC, but you've shown me a case that just... wow. I can't imagine trying to make a computer system integrate with that style of timekeeping. Is there any hope? Or is it actually the solution to give up and switch to something a bit easier like the Gregorian calendar (or whatever)?
    - amerkhalid 10y ago
      I think most of the Muslims have already given up and follow Gregorian calendar for all purposes but religious holidays. I grew up in Saudi Arabia and I can tell you that no one ever knew current month in Hijri calendar unless it was Ramadan or Muharram (1st month).
    - gumby 10y ago
      > wow. I can't imagine trying to make a computer system integrate with that style of timekeeping. I don't mean to harsh on you but I feel you have it completely backwards. The computers should do the heavy lifting to adapt to how people want to live, not the other way around. If people want flexible calendars that optimize for strange things let the computers do the heavy lifting for them. I have been quite sorry when countries have attacked their languages or even alphabets in a misguided way to support computers (consider the letters ll and ch in Spain which were "reformed" just in time for the "improvement" to become irrelevant) when the responsibility lies with the computer. This is not only a computer issue: cities and suburbs were restructured for automobiles, and even the law changed (the invention of "jaywalking" at the behest of car manufacturers) rather than forcing the machines to adapt to the needs of humans. Technodeterminism is simply a weakness of will.
      - lemmings19 10y ago
        You suggest making absolutely no compromises in order to move technology forward? Not everything we do is without question; we do some pretty dumb stuff. Why not improve our systems where it makes sense to?
        gumby 10y ago
        Almost, yes. Certainly I advocate that the technology adapt much much much more to humans than the other way around! After all, who decides what "improvement" is? The cry of "progress!" has resulted in plenty of destruction as well as benefit, not to mention mountains of premature optimization (think of those elevated freeways into cities that created dead zones and had to be dismantled only decades later, or for that matter the alphabet changes I mentioned). We used to vary the length of the hour; now we have a second that is fixed and we vary the length of the human day in order to match the rotation of the earth. I happen to think that's a good optimization but I have friends who argue vociferously that those leap seconds are a bad idea. Who's right (hint: on all topics I am). And there are no absolutes: some languages let their spelling fluctuate (e.g. English), some fix it somewhat rigidly (e.g. French) and some change it systolicly to re-align with perceived practice (e.g. German) -- who is right? I speak all three daily and frankly I consider the German practice the worst of the three. But enough people prefer it so why not? Sure there's tons of stupid practice (e.g anti-vaxxers). But at the end of the day technology (τέχνη) is an art in service of humans, not the other way around. And to tie this back to HN: if a business doesn't think that way it will not survive.
- a3n 10y ago
  What is a day, when does it start and end, etc, have various definitions around the world and in history. https://books.google.com/books/about/Calendrical_Calculations_Millennium_Edit.html?id=5r_kSKE4OdYC https://books.google.com/books/about/Calendrical_Calculation... Calendrical Calculations is a fascinating intro the different calendar systems, along with computational methods of converting between systems.
- wolf550e 10y ago
  This is the same as the early Jewish calendar. The Jewish calendar has adjustments to make it not fully lunar, so that holidays would be during the same season every year, unlike in the simpler Muslim calendar which is fully lunar. The bible says the new moon must be observed, but the formula for the calendar was calculated in 389CE and that requirement was not observed. I was taught they switched to the calculated calendar right then, but wikipedia says newer sources show the switch was a gradual process that lasted until the 9th century CE. https://en.wikipedia.org/wiki/Hillel_II https://en.wikipedia.org/wiki/Hillel_II
midhunsezhi 10y ago
TIL that people grumble about California.

HCIdivision17 10y ago

I had no idea there was that sort of requirement - I guess I had just assumed it was systemized. It sounds fascinating - are there ever conflicts that need to be resolved?

amerkhalid 10y ago
All the time. You will see Muslims in a same city celebrating same festival a day apart. I think some serious Muslims get into arguments but most people just enjoy an extra day of festivities.
- HCIdivision17 10y ago
  I have long held that there aren't any good solutions to the date/time issue (like naming things and cache invalidation :), other than just find some way to hitch to UTC, but you've shown me a case that just... wow. I can't imagine trying to make a computer system integrate with that style of timekeeping. Is there any hope? Or is it actually the solution to give up and switch to something a bit easier like the Gregorian calendar (or whatever)?
  - amerkhalid 10y ago
    I think most of the Muslims have already given up and follow Gregorian calendar for all purposes but religious holidays. I grew up in Saudi Arabia and I can tell you that no one ever knew current month in Hijri calendar unless it was Ramadan or Muharram (1st month).
  - gumby 10y ago
    > wow. I can't imagine trying to make a computer system integrate with that style of timekeeping. I don't mean to harsh on you but I feel you have it completely backwards. The computers should do the heavy lifting to adapt to how people want to live, not the other way around. If people want flexible calendars that optimize for strange things let the computers do the heavy lifting for them. I have been quite sorry when countries have attacked their languages or even alphabets in a misguided way to support computers (consider the letters ll and ch in Spain which were "reformed" just in time for the "improvement" to become irrelevant) when the responsibility lies with the computer. This is not only a computer issue: cities and suburbs were restructured for automobiles, and even the law changed (the invention of "jaywalking" at the behest of car manufacturers) rather than forcing the machines to adapt to the needs of humans. Technodeterminism is simply a weakness of will.
    - lemmings19 10y ago
      You suggest making absolutely no compromises in order to move technology forward? Not everything we do is without question; we do some pretty dumb stuff. Why not improve our systems where it makes sense to?
      - gumby 10y ago
        Almost, yes. Certainly I advocate that the technology adapt much much much more to humans than the other way around! After all, who decides what "improvement" is? The cry of "progress!" has resulted in plenty of destruction as well as benefit, not to mention mountains of premature optimization (think of those elevated freeways into cities that created dead zones and had to be dismantled only decades later, or for that matter the alphabet changes I mentioned). We used to vary the length of the hour; now we have a second that is fixed and we vary the length of the human day in order to match the rotation of the earth. I happen to think that's a good optimization but I have friends who argue vociferously that those leap seconds are a bad idea. Who's right (hint: on all topics I am). And there are no absolutes: some languages let their spelling fluctuate (e.g. English), some fix it somewhat rigidly (e.g. French) and some change it systolicly to re-align with perceived practice (e.g. German) -- who is right? I speak all three daily and frankly I consider the German practice the worst of the three. But enough people prefer it so why not? Sure there's tons of stupid practice (e.g anti-vaxxers). But at the end of the day technology (τέχνη) is an art in service of humans, not the other way around. And to tie this back to HN: if a business doesn't think that way it will not survive.
a3n 10y ago
What is a day, when does it start and end, etc, have various definitions around the world and in history. https://books.google.com/books/about/Calendrical_Calculations_Millennium_Edit.html?id=5r_kSKE4OdYC https://books.google.com/books/about/Calendrical_Calculation... Calendrical Calculations is a fascinating intro the different calendar systems, along with computational methods of converting between systems.
wolf550e 10y ago
This is the same as the early Jewish calendar. The Jewish calendar has adjustments to make it not fully lunar, so that holidays would be during the same season every year, unlike in the simpler Muslim calendar which is fully lunar. The bible says the new moon must be observed, but the formula for the calendar was calculated in 389CE and that requirement was not observed. I was taught they switched to the calculated calendar right then, but wikipedia says newer sources show the switch was a gradual process that lasted until the 9th century CE. https://en.wikipedia.org/wiki/Hillel_II https://en.wikipedia.org/wiki/Hillel_II

midhunsezhi 10y ago

TIL that people grumble about California.