17 ms·

Australia/Lord_Howe is the weirdest timezone

• benreesman 2y ago
  So this is a thing: I caught the Snake emoji behaving differently in some code because it was coded one thing before #celebrity-thing, and the opposite months later. Snake Emoji Kanye vibes are the weirdest timezone.
  • pests 2y ago
    Wait, how is it different before/after?
• surfingdino 2y ago
  I love time/date problems. One of the best references on the subject of calendars is "Standard C Date/Time Library: Programming the World's Calendars and Clocks" by Lance Latham. He really goes into a lot of detail on various calendaring systems, some really cooky, https://amzn.to/4hjv5L3 https://amzn.to/4hjv5L3 BTW. A long, informative post without a single mention of AI. A rare thing these days.
  • notachatbot123 2y ago
    Clean link without affiliate code: https://www.amazon.co.uk/Standard-Date-Time-Library-Programming/dp/0879304960 https://www.amazon.co.uk/Standard-Date-Time-Library-Programm...
• spockz 2y ago
  I really love this way of writing. Informational with occasional bits of humor. It makes it read and ingest.
  • ides_dev 2y ago
    Absolutely agreed, it’s a really nice conversational tone. It is technical without being dry and entertaining without watering down the information. I strive to write like this.
  • Semaphor 2y ago
    Agreed, and the humor is restrained. Often there are posts (which tend to also have an annoying amount of gifs) which just overdo it. But here it’s neatly used to lighten the writing.
  • jccalhoun 2y ago
    I guess I'm alone. I HATED it.
  • ucarion 2y ago
    You should read Matt Levine's Money Stuff! I think his is the tone I roughly was going for here.
• captn3m0 2y ago
  The tz-iana mailing list is a lot of fun to subscribe to.
• Terr_ 2y ago
  To me, one of the key framing ideas that almost all dates/times are actually a set of matching-rules that you are monitoring for. You can guess how many seconds will elapse until the match triggers, but you can't be totally sure [0] until it happens, and in some cases it will never quite happen at all. [1] Then the second half is often to reverse your "I think it will happen X seconds from now" delta-guess into "I'm also guessing that your timezone's clocks will say Y when it happens." Just don't forget to keep track of which timezones is controlling the event versus which timezones it is being displayed in. ____ [1] Your UTC estimate might occur plus or minus leap seconds. TAI is safer, unless somebody discovers something exciting and new that changes the behavior of cesium atoms. [0] Such as if the time zone vanishes because the country is gone. Or perhaps the 1:30 to 2:00 thing couldn't exactly happen because the clocks went forward from 1:00 to 2:00 with a missing hour.
• deleted 2y ago
  [deleted]
• ryzvonusef 2y ago
  Reminds me of when Tom Scott descended into madness at trying to account for time zones: https://www.youtube.com/watch?v=-5wpm-gesOY https://www.youtube.com/watch?v=-5wpm-gesOY
  • luoc 2y ago
    Somehow I end up watching this about twice a year
• import 2y ago
  Nice morning reading
• prmoustache 2y ago
  In my opinion, the best way to see it is not to pretend their are weird timezones. It is not because most of the world do summer time and that when they do they have a 1h transitions that we should take it for granted. This article do not mention the Chatham Standard Time Zone from Chatham Islands archipelago in NZ which is 45 minutes ahead of New Zealand Daylight Time, nor the Central Western Standard Time (Australia/Eucla). Also wikipedia mention there is a "train timezone" for the Indian Pacific train. I wonder if other trains have a dedicated timezone?
  • sakjur 2y ago
    > I wonder if other trains have a dedicated timezone? They used to, railway time is how our timezone system came to be.
  • reisse 2y ago
    > It is not because most of the world do summer time Eh? Most of the world don't do summer time.
    • prmoustache 2y ago
      Yes for some reason I read the following sentence backwards thinking that 410 timezones were observing DST while 185 did not. > Hmm. 410 timezones just don’t DST at all. 185 have a 3600-second, i.e. 1-hour, difference. My point stands that there is no normality, just governments taking different decisions and being entitled to it and what the majority does is not relevant.
    • ComputerGuru 2y ago
      Is that also true by population?
      • reisse 2y ago
        Sure. The only country from the top ten by population that observes the DST is the US. From the top fifteen countries, it's US and Egypt. I think the statement is true by any reasonable metric - population, land area, GDP size.
• lifthrasiir 2y ago
  > These time zones have hundreds of hard-coded transitions out into the future. I don’t understand why, it’s not like they all have lunar calendar stuff going on. Without any additional update to the tz database, all annual transitions are assumed to continue indefinitely. So TZif version 1 would repeat transitions up to January 2038 (i.e. the end of signed 32-bit time_t), while version 2 or later would keep them for the compatibility (see the section 4 of RFC 8536) but also include the algorithmic description in the footer for later dates.
• radekk 2y ago
  I wonder why the dst transition hours are encoded in local time. Wouldn't it be easier to do it in UTC? There is no need to differentiate between the same hour before and after change then.
  • winternewt 2y ago
    Perhaps to decouple DST transition rules from other time-zone changes. So if the time-zone offset is adjusted for some other reason then the DST rule does not also need to be changed.
  • taneliv 2y ago
    Suppose in local time (which is, say, UTC+3) the DST transition is on something like "last Sunday of 10th month at 02:00", which might then in UTC become "last Saturday of 10th month at 23:00, except if that Saturday is the last day of the month, then the second to last Saturday". In effect, if conversion to UTC causes the transition to move to a different day, it might also be on a different week or month, causing headache. (Or did you ask something else entirely? It wouldn't be the first time I misunderstood things about time zones.)
  • blahedo 2y ago
    I bet it's North America bias—we roll our time changes across the continent one TZ at a time, at 2am local time (which also explains why the default is "/2").
• Scarblac 2y ago
  I'm going to steal "Greenland is part of the greater EU cinematic universe".
• guidedlight 2y ago
  Nah, the weirdest time zone is Africa/Addis_Ababa, which nobody in Ethiopia follows. Instead the locals offset the time by 6 hours. So the AM cycle starts at dawn (i.e. 6am), and the PM cycle starts at dusk (i.e. 6pm). https://en.wikipedia.org/wiki/Time_in_Ethiopia https://en.wikipedia.org/wiki/Time_in_Ethiopia
  • squiggleblaz 2y ago
    Sounds like it could be a candidate. Any system which can't be expressed in standard software is stranger than every system that can be.
    • dangsux 2y ago
      [dead]
    • dpassens 2y ago
      But whether standard software is able to express this system is up to the software, not the system, no? Why is this way of timekeeping weird, apart from the arbitrary decision not to support it?
      • tankenmate 2y ago
        The decision to not support it isn't "arbitrary" per se; it's a function of utility vs cost to implement (which a healthy dose of fudge). "Standard software" for timekeeping is far more useful precisely because it is used by far more people.
        • dpassens 2y ago
          Maybe arbitrary was the wrong word. I understand that this is an implementation cost issue and I'm not saying that the decision not to pay this cost wasn't reasonable. My objection is not with tzdb, but with the characterisation of a real-life practice as weird just because software doesn't accommodate it. Shouldn't what people do be the reference for what is normal, rather than the rules encoded in software?
• squiggleblaz 2y ago
  I kind of thing a half hour daylight savings difference instead of an hour is a pretty low bar for the weirdest timezone. Almost any of the others are weirder: Antarctica/Troll definitely sounds weirder. The Moroccan and Gazan timezones that can't be expressed by the system as it was written because at least that means that they have some different kind of a rule, even if lunar time is well known. Same with the ones that are in Apple's naughty list because they're transitions the day before some day - again, not very weird, but at least it's weird enough to break things. But I do agree with leap seconds: it's absolute trivia, not a useful thing for a programmer to know. Your computer smears them and you don't even know when they happened. You could completely forget them. Except that countries transitioned from ignoring leap seconds to considering them, so the switch in Australia from "GMT+x" to "UTC+x" a couple of decades ago was the transition from ignoring leap seconds to incorporating them. The fact that this is almost universally ignored is probably for the better.
  • michaelt 2y ago
    > But I do agree with leap seconds: it's absolute trivia, not a useful thing for a programmer to know. By and large, I agree with this. But I've always found it a bit funny when a large organisation [1] says "our servers have sub-millisecond timing accuracy, thanks to GPS synchronization and these PCIe rubidium atomic clock cards we've developed" while at the same time saying [2] "we smear leapseconds over the course of a day, in practice it doesn't matter if a server's time is off by ±0.5 seconds" [1] https://engineering.fb.com/2021/08/11/open-source/time-appliance/ https://engineering.fb.com/2021/08/11/open-source/time-appli... [2] https://engineering.fb.com/2020/03/18/production-engineering/ntp-service/ https://engineering.fb.com/2020/03/18/production-engineering...
    • growse 2y ago
      The thing that super accurate timestamps buys you is common agreement across your infrastructure as to what the time is. This basically makes distributed systems work faster/better/whatever. The relation between that time and what the rest of the world thinks the time is is actually less relevant.
    • 2y ago
• floitsch 2y ago
  I implemented `DateTime` in Dart and Toit and wrote a blog post about the things I noticed: https://medium.com/@florian_32814/date-time-526a4f86badb https://medium.com/@florian_32814/date-time-526a4f86badb Timezones are fun...
• trollied 2y ago
  https://en.wikipedia.org/wiki/Sandringham_time https://en.wikipedia.org/wiki/Sandringham_time was a crazy one
• fouronnes3 2y ago
  What I like about the tz database is that's it's technically a diff of a diff. It stores the difference across history, of the difference of each timezone with UTC. Right? So it's a diff^2. But! The tz database gets updates! So those commits are diffs of diffs of diffs, or diff^3. Can we go further? You bet! It has a changelog, and that changelog is stored in git, so commits to the tz changelog are diff^4: they are changes to the list of changes to the list of changes to the list of changes to UTC.
  • dalmo3 2y ago
    You forgot that UTC (or timekeeping in general) itself is a diff.
    • fouronnes3 2y ago
      Oh that's a great point! We have achieved diff^5 at last! Now that I think of it, we could even stretch it one more level. In practice UTC is "realized" as a "best of" diff to atomic clocks in labs around the world, which are themselves diff against a fixed time point, as you pointed out. So that realization technically changes when the official UTC bulletin[1] is published by BIPM. So diff^6! [1] https://www.bipm.org/en/time-metrology https://www.bipm.org/en/time-metrology
      • hhdhdbdb 2y ago
        Can we bring relativity in for another diff :)
      • flippyhead 2y ago
        Yes, but, it's always 5 o'clock somewhere, amiriiight??
      • Yossarrian22 2y ago
        Don’t forget using GPS to get the time and tell you if you’ve crossed time zones
        • 2y ago
• jiggawatts 2y ago
  Oh wow, what a coincidence, I was just looking at Lord Howe Island on a map of species conservation. For anyone who doesn't know: Lord Howe Island is the last true paradise on Earth. I went there on holidays a few years back based on two travel review recommendations. Both were by professional travellers that had been to pretty much everywhere, and both said it's the best place they've ever been. The reasoning was that every other tropical island has "something" wrong with it. Pushy locals trying to sell you stuff, sharks in the water, malaria, pollution, crime, poverty, or something. Lord Howe is about as safe as it's possible to get, civilised beyond belief, pristine, unpolluted, etc... It's one of the last places in the world with undamaged, unbleached coral reefs in protected waters. The diving there is just unbelievable, more beautiful than any Planet Earth documentary you've seen. Birds nest on the beach, and you have to step over them gently because there's thousands of them and the juveniles can't fly yet. I met the police officer of the island and pointedly asked him when was the last time he had to deal with crime. "Crime... crime... let's see." he said, counting on his fingers slowly "Umm... seven years ago there was a domestic violence report because a tourist slapped his wife in an argument." The hotel doors have no locks. There's $500 in cash in a tin next to a shack full of equipment on the beach with a "honesty system" rental price list sign next to it. The bloke selling you coke cans at the milk bar bought it with the $20 million he made in the stock market. Half the tourists go there by private plane. Ballmer's son took his super yacht there with a harem of models. And on, and on. If you ever get the opportunity to visit: GO!
  • ascorbic 2y ago
    > Half the tourists go there by private plane. Ballmer's son took his super yacht there with a harem of models. Sounds great apart from that bit.
    • jiggawatts 2y ago
      He's not there all the time!
  • hakfoo 2y ago
    But did you see the stick insects?
• djaychela 2y ago
  Oddly was just reading something yesterday and it mentioned that in the UK there were years during the war where we had double DST for energy saving reasons. (although we went between 1 hour and 2 hours, so it was only really a change compared to the norm) https://www.atlasobscura.com/articles/the-extreme-daylight-savings-time-of-world-war-ii https://www.atlasobscura.com/articles/the-extreme-daylight-s...
  • IshKebab 2y ago
    I don't really understand how that would save energy. Did people work 7am-3pm days or something?
    • hnbad 2y ago
      The idea behind DST is that it shifts working hours into daylight hours during the darker months. This would theoretically cut down on energy use for lighting during those hours. Of course offices, factories and even schools still use artificial lighting even during daylight hours. And now the energy use of artificial lighting is much lower than back when everything used filament.
      • shultays 2y ago
        Even ignoring the energy saving part, it sucks waking up and leaving for work or school while it is still dark. A while ago Turkey switched to a different timezone and stopped doing DST for reasons and now everyone was waking up one hour early in winters. Considering how bad traffic is in larger cities that meant a lot of people will be waking up and going to work or school while it is still dark.
        • hnbad 2y ago
          EEST (DST) is UTC+3, EET (without DST) is UTC+2. What Turkey did was abolish the DST transition but stay in permanent DST time or "summer time", which they now call TRT (which is identical to EEST). There was a survey in parts of the EU a few years ago about abolishing DST that came out largely in favor of abolishing it. In Germany one major source of debate around the issue was that the survey referred to the timezones as "winter time" and "summer time" and predictably more people said they would prefer permanent "summer time". An equivalent survey referring to the timezones as "standard time" and "daylight savings time" likely would have had the opposite result. I could imagine that Turkey picked EEST instead of EET for similar reasons. Having had a job for six months over the winter where I spent the majority of the 8 hour work day underground, which at times meant I'd go for days without seeing proper sunlight, I agree that this is just miserable.
• twelvechairs 2y ago
  Along with Kathmandu for weird offsets is Australian Central Western Standard Time (UTC +8:45), used in a tiny area of Australia with the largest town being Eucla (population 37). Being mainly within Western Australia (which doesn't use daylight savings) but partially within South Australia (which does use daylight savings) there has also been informal use of UTC+9:45 Historically there was also Dublin mean time (UTC -00:25.21) and Warsaw mean time (UTC+1:24)
  • ajdlinux 2y ago
    An interesting aspect of ACWST is that it has no legal status - it's observed purely by local convention, though it's still managed to make it into tzdata.
    • antisol 2y ago
      indeed! and not only is it in tzdata, there are signs on the road telling you about it
• LysPJ 2y ago
  > America/Nuuk does daylight savings at -01:00 (yes, with a negative) Somewhat related: Europe/Dublin has a negative DST offset. Irish DST runs through the European winter (i.e. the opposite of the other European timezones). (More details here: https://github.com/golang/go/issues/56743#issuecomment-1315735706 https://github.com/golang/go/issues/56743#issuecomment-13157... ) Edit: To be clear: the quote is referring to a negative DST start, rather than a negative DST offset.
  • hnbad 2y ago
    I think you misread that. America/Nuuk doesn't have reverse DST (which is easily solved by just switching DST and non-DST around). It starts DST at a negative offset because the offset is defined as relative to the previous day.
    • LysPJ 2y ago
      Yes, this is indeed a different situation and my comment doesn't make that clear. Thank for pointing that out. I've made an edit.
  • extraduder_ire 2y ago
    In the github repo the article links, there is a large number of comments about the Europe/Dublin time zone in the europe file, including one quote from Ulysses: https://github.com/eggert/tz/blob/7748036bace8562b9c047f368c8eba5f35e8c4b4/europe https://github.com/eggert/tz/blob/7748036bace8562b9c047f368c...
• bjoli 2y ago
  A friend of mine has been visiting places with weird time related things going on, because it is interesting and takes you funny places. He has been to Lord Howe. Now I know why. He has a user account on HN. I will ask him if he wants to make an appearance here...
  • dv35z 2y ago
    Please do! Announce his arrival using his favorite time zone, and see if we can figure it out...
• uludag 2y ago
  > Wrote a script in emacs lisp to calculate Ramadan I found this pretty funny, but a spot on solution. The solar/calendar features of Emacs are surprisingly robust and easy to work with.
• imrejonk 2y ago
  I find it slightly ironic that a blog that’s educating (and entertaining) us on time and timezones does not itself mention when its blogposts were published, at least on mobile. This one appears to have been published in the summer of 2024.
  • rozenmd 2y ago
    Seems like pretty timeless content to me.
    • tuoret 2y ago
      There's a couple of things that made me think the article was way older than it actually is (and made me mildly irritated that it doesn't include the publication date). First off, the author starts off by talking about GMT and goes on to educate the reader how UTC is actually the current standard. Maybe it's just me but I thought this would be common knowledge by now, while the author frames this as some sort of a revelation. Then there's the jab about The IERS breaking Wikipedia's css which just doesn't seem to happen on the two devices I opened it on, so I assumed that was the case prior to Wikipedia's redesign. Minor things for sure, and the content itself is pretty timeless (heh).
      • SAI_Peregrinus 2y ago
        Leap seconds are also set to be removed eventually. UTC will become UT1 with a fixed offset, at least until enough seconds add up for the BIPM to care about the offset and insert a leap minute or hour or something TBD.
        • zokier 2y ago
          > UTC will become UT1 with a fixed offset I'm not sure what you mean, but this sounds wrong. The whole thing about leap second abolishment is to effectively disconnect UTC from UT1, i.e. allow DUT1 to grow unbounded and make UTC a fixed offset of TAI.
• alexjplant 2y ago
  Earlier this year I had to write a function to find the current local time given a US address. The naive way to do so would be via a static mapping of state to time zone but there are a few edge cases that preclude doing this; in the interest of cost and speed relative to this specific application I spent a few dollars on a CSV that maps every US ZIP code to UTC offset and whether DST is followed (among other data). pytz takes IANA timezone names so I ended up having to map offset and DST info manually to specific timezones. As it turns out the US has a fair number of weird edge cases for overseas territories and military bases that necessitated the use of things like "Etc" zones [1] that have funky semantics (because of Unix for some reason if Wikipedia is to be believed). [1] https://en.wikipedia.org/wiki/Tz_database#Area https://en.wikipedia.org/wiki/Tz_database#Area
  • koliber 2y ago
    A good approach would be to map a zip code to the named timezone (e.g. US/Eastern). Then, if you need to produce the UTC offset, apply the timezone to a date using pytz and get the offset. The named timezone is special as it is constant. The UTC offset timezone (e.g. "-05:00") and the shorthand name (e.g. "EST") is NOT constant over time for a given location, because of daylight savings time. "US/Eastern" flips between "-05:00" and "-05:00", as well as between "EDT" and "EST". If you ask someone what their timezone is and offer them offsets or the short names, it causes confusion for everyone.
  • hocuspocus 2y ago
    > The naive way to do so would be via a static mapping of state to time zone but there are a few edge cases that preclude doing this More than a few, state is really the wrong resolution here, US timezones follow counties and native reservations borders. ZIP codes should probably be good enough but I'd be careful too. If your volume of addresses isn't too crazy, the robust way is to reverse geocode them and use a library that gets you the IANA identifier from timezone shapes. https://github.com/RomanIakovlev/timeshape https://github.com/RomanIakovlev/timeshape is maintained by a former coworker who could open source some of the work we did internally.
    • 2y ago
• __alexs 2y ago
  I think the old Riyadh timezone is the weirdest personally https://github.com/eggert/tz/blob/be62d5918223b4df209cc941633b8c5b80cc0d20/asia#L3784-L3826 https://github.com/eggert/tz/blob/be62d5918223b4df209cc94163...
  • NelsonMinar 2y ago
    agreed. From pytz's docs: "the intention was to set sunset to 0:00 local time, the start of the Islamic day. In the best case caused the DST offset to change daily and worst case caused the DST offset to change each instant depending on how you interpreted the ruling"
  • ucarion 2y ago
    If you go by the wtf-ness of the comments on a tz, Asia/Riyadh has gotta be up there. But contemporarily it behaves as `<+03>-3`, which is vanilla.
• bob1029 2y ago
  The Japanese calendar has always been the most fascinating date/time thing for me: https://devblogs.microsoft.com/dotnet/handling-a-new-era-in-the-japanese-calendar-in-net/ https://devblogs.microsoft.com/dotnet/handling-a-new-era-in-...
• bradley13 2y ago
  Hard-coded yearly transitions for a particular region, because they just have to have their own, special rules? Transitioning to DST on Sunday at -01:00 (minus one o'clock)? Or at 24:00? Honestly, the IT world has a certain amount of influence. There comes a time where we could collectively just say "no". No, you are not that special, use any of the already incredibly flexible options that you have.
  • magnio 2y ago
    > There comes a time where we could collectively just say "no" Well, C23 mandates a byte is 8 bits, and POSIX 2024 disallows newlines in filename, so we do exercise that right times to times.
  • growse 2y ago
    I think you've got who's serving whom the wrong way round.
• szemy2 2y ago
  > With a “designator” time that doesn’t mean much This might not 'mean much' to the computer, but it means a lot to the human. The computer uses it to communicate with the human and the humans between each other. When I arrange a meeting across timezones I will say CET 16.00 or ET3.00PM and they will understand it faster than saying how much offset we are from UCT.
• jamiehall 2y ago
  > Btw it’s called UTC (Universal Time Coordinated? huh?) because the same folks who publish UTC also publish UT1, which is UTC sans the leap seconds. I’m not sure that’s right! According to legend among metrologists I’ve talked to, “UTC” was chosen as a compromise candidate: it makes sense as an acronym in neither English nor French.
  • samatman 2y ago
    So like ISO, then. Which is not an acronym, btw, it's just styled in all caps, and is to be pronounced "iso" rather than "eye-ess-oh".
• nokeya 2y ago
  I always say that timezones and font rendering are the most sucking problems that developer can encounter. Both have a ton of weird quirks, both implemented differently across various target devices/OSes and require a lot of time and effort to implement reasonably right.
• ChrisMarshallNY 2y ago
  I’ve found the best way to deal with TZ conversions, is to use UTC as a common fulcrum. I convert the target TZ to UTC, using my local utility, then use my local TZ utility to convert from UTC to local. But I write iOS software, so I have very solid local tools at hand. It might be more problematic, on, say, a webserver. On a related note, I wrote this utility[0], some time ago. It uses the TZ map from the TZ Boundary Builder project[1]. [0] https://github.com/LittleGreenViper/LGV_TZ_Lookup https://github.com/LittleGreenViper/LGV_TZ_Lookup [1] https://github.com/evansiroky/timezone-boundary-builder https://github.com/evansiroky/timezone-boundary-builder
  • klysm 2y ago
    UTC is generally a good idea for storing, but there are still some ways to have that bite you. If a user enters a local date time for a future event in a particular time zone, converting that to UTC could result in incorrect behavior if the timezone definition changes. It depends on if the user meant that UTC time or if they meant the local time.
    • ChrisMarshallNY 2y ago
      That's why I do it at the time the query is made. I don't ever store UTC.
    • bmicraft 2y ago
      > if the timezone definition changes Or if DST kicks in/out. No need to have the definitions change.
      • klysm 2y ago
        Depends on how naive the conversion is. If you consider DST while making the conversion that’s not really a problem
    • Ndymium 2y ago
      It can also cause trouble if you store past events but do not store the user's local offset or timezone at the time of the event. If you aggregate these events later into a dataset of "events by hour", they may be grouped wrong (from a user's perspective) if you convert them all to the user's _current_ timezone.
• tankenmate 2y ago
  "Running cron jobs on an hourly basis doesn’t in practice have very weird interactions with DST" Of course every sane person runs their default system clock on UTC and lets users pick their own local time. That way cron always does the "right thing"(TM).
  • rubenv 2y ago
    That's true if you need to clean up temporary files every night or make a backup. But what if your cronjob has an effect in the physical world, locally? E.g. open the parking gates every morning. The world is inherently messy :-)
    • roryirvine 2y ago
      That sort of thing would be best handled by your own user's crontab, so would naturally inherit that user's TZ. If you must run it as root, you can specify a CRON_TZ variable on a per-file basis, which will override the default.
    • tankenmate 2y ago
      Well assuming that the gates don't move timezones. But obviously jobs that need to run for a given timezone should be configured to run in that timezone.
      • cube00 2y ago
        Unless the gates need to open at 2:30am and in the case of daylight savings time that hour is skipped.
        • tankenmate 2y ago
          Not if that cron file (you can have multiple cron files per user/system) is configured to run in the local timezone.
          • sib 2y ago
• vander_elst 2y ago
  I still hope that someday the whole world will run on UTC0 and there is no more time zones madness. I know the day will likely never come but I like to keep dreaming.
  • sethammons 2y ago
    Some dates will change when at relatively strange times. For some, the date change will be two hours into the workday. That seems odd. And you lose some info too: if I want a 07:30 (am) meeting, is that during the working hours of my target location? With offsets, I can see that it is 12:30pm at my target location and know that I am scheduling over lunch very likely. With no timezones, how do I know what time of day it is there? Recall some anchor time and do mental math each time? "Morning in London is 13:00, so four hours later right before lunch is 17:00, and for an LA meeting, let's see, morning there is 05:00, so 17:00 is evening time, I think
    • vander_elst 2y ago
      > the date change will be two hours into the workday. That seems odd Seconds minutes and hours can change but the day cannot? > mental math each time Usually meetings are setup using an app and shared calendars should actually help here, a person can have meeting slots and out of office time, that should provide the same info. logistically I don't see that much of a difference from the current situation
      • iggldiggl 2y ago
        > Seconds minutes and hours can change but the day cannot? The calendar day being aligned to the sleep/wake cycle and changing when most of the population is either asleep or at least might not terribly care about the actual date does help quite a bit. > Usually meetings are setup using an app and shared calendars should actually help here, a person can have meeting slots and out of office time, that should provide the same info. logistically I don't see that much of a difference from the current situation It'd also wreck any time references in any kinds of stories that aren't consumed locally. So every time I read/watch/listen to a story that isn't set where I live, I'd first have to look up the local time to make sense of any time references.
• stevage 2y ago
  This is awesome - I have always kind of wondered how this stuff was implemented, but never looked it up.
• azernik 2y ago
  The "Asia/Jerusalem" weirdness is because Daylight Savings Time is a big church-and-state issue. Religious people want the workday to be convenient for holidays that start at sunset. This led to decades (up to the mid-'00s) where Daylight Savings was the result of annual negotiations between religious and secular parties. It often caused problems when the decision wasn't made until juuuust before the transition date. There are still exceptions built in to prevent Daylight Savings from ending on Rosh HaShanah, so that's probably the future stuff.
  • rob74 2y ago
    Reading this, and considering the limited advantages of DST (especially for a country that is relatively far to the south), I wonder why they didn't decide to scrap DST completely? Maybe they will if the EU eventually manages to do it?
    • lazide 2y ago
      If they didn’t have that to argue about, what else would they do with their spare time?
    • maratc 2y ago
      I would argue that DST actually makes most sense in 30-40 degrees of latitude. With about 13 hours of sunlight in the summer, split evenly around the mid-day, it comes down to 05h30 to 18h30 under light. There are many more people who would be out there to enjoy the sunlight between 18h30 and 19h30 than there are between 05h30 and 06h30.
      • bena 2y ago
        I really dislike this argument of "I'd rather enjoy the sun in the evening than in the morning" ignoring all of the other problems it causes. Sunlight in the morning is useful. It's better for your sleep rhythms. It's safer for school children, etc. And to be completely fair, I don't see that many more people "enjoying the sunlight" during the weekend when they have the entire day to do so. Like, what is the sun going down at 6 really preventing you from doing that you couldn't do otherwise?
• entuno 2y ago
  The time zone in Palestine is a bit weird as well: https://en.wikipedia.org/wiki/Time_in_the_State_of_Palestine https://en.wikipedia.org/wiki/Time_in_the_State_of_Palestine They have DST, but it's not on fixed dates, the government just announces each year when it's going to start and end. Sometimes with less that a week's notice, which must cause all kinds of interesting problems for people.
  • yokoprime 2y ago
    Without getting deep into politics I don't understand why they would prioritize spending effort on DST at all, seems like there are plenty of other concerns.
    • DoughnutHole 2y ago
      If your life is dominated by an us vs them dynamic small demonstrations of difference become hugely important. In a similar vein different people in Xinjiang in China observe entirely different timezones - Han Chinese observe Beijing time (because China is insane and uses one timezone despite spanning 5), while Uyghurs observe a local time 2 hours behind. It’s a small show of resistance, which is sometimes all a people have if they have limited control of their own affairs.
    • jdietrich 2y ago
      Again, without wanting to get too political, I think it's essentially bikeshedding. The Palestinian National Authority is riven with factional conflicts and has very limited state capacity. That almost inevitably leads to a lot of bickering over largely irrelevant decisions as a symbolic but hollow demonstration of political authority. The ability to make the decision takes on an importance completely out of proportion with the actual significance of the decision.
    • grotorea 2y ago
      I don't see why announcing DST would be a big effort. And it saves on electricity costs.
      • 2y ago
• deleted 2y ago
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• dfc 2y ago
  Does anyone understand what was meant by "This is because almost every standard (except ISO8601, whatever) is just a file, and you can read it." Initially I thought it was because the PDF of ISO-8601 is not a file commonly distributed with operating system. But that's not unique to ISO8601, you won't find IEEE 1588-2019 or NMEA 0183 v4.11 on your computer either. For ~20$ I think I can buy a PDF of the standard from ISO. Is there something special about ISO8601 that is not contained in the standard?
  • NeoTar 2y ago
    Possibly joking about the .iso file-type for optical disc images? Or maybe that 'most' ISO standards that are encountered by engineers are defining file-types. I'm also a big fan of ISO-3166 though !
  • sundarurfriend 2y ago
    I believe the IEEE and others also would come under the exceptions to the "almost" - anything you'd have to make a special effort to seek out and purchase. > Don’t let people bully you into thinking that just because something is complicated, it’s impossible. > This is because almost every standard (except ISO8601, whatever) is just a file, and you can read it. In context, (my interpretation is that) "standard" includes things like The Time Zone Information Format [1], the GNU docs about TZ [2], etc. I think the idea is to say "the documents laying out the details of complicated things are still just documents, you can read them if you're interested and don't have to just see them as meant of domain experts. Some of them have barriers to access like the ISO documents, but even excepting those you have direct access to most everything you might want to understand, don't let the idea of standards intimidate you." [1] https://www.rfc-editor.org/rfc/rfc8536.html https://www.rfc-editor.org/rfc/rfc8536.html [2] https://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html https://www.gnu.org/software/libc/manual/html_node/TZ-Variab...
  • lozf 2y ago
    > For ~20$ I think I can buy a PDF of the standard from ISO. You might find most standards for ~20 USD, but ISO8601 direct from iso.org will set you back 173 CHF (~200 USD) for part 1¹, 194 CHF (~220 USD) for part 2². For $20 you get only the latest amendments from them. Meanwhile the Estonians will gladly sell you their version of part 1 for just under 30 USD.³ ¹: https://www.iso.org/standard/70907.html https://www.iso.org/standard/70907.html ²: https://www.iso.org/standard/70908.html https://www.iso.org/standard/70908.html ³: https://www.evs.ee/en/evs-iso-8601-1-2019 https://www.evs.ee/en/evs-iso-8601-1-2019
• aleksi 2y ago
  The most interesting timezone I ever encountered is Europe/Moscow on and around January 1, 1900. If you decide to use that date as a zero date in your code (for example, to handle the transition from two digits per year), you will be in a lot of pain: the offset was +02:30:17. Yes, with 17 seconds! Demo: https://go.dev/play/p/lq36Plr1sIL https://go.dev/play/p/lq36Plr1sIL
  • iso8859-1 2y ago
    The tzdb assumes Local Mean Time (LMT) was used all over. For example, the tzdb has Africa/Monrovia still using LMT in 1970. https://en.wikipedia.org/wiki/Local_mean_time https://en.wikipedia.org/wiki/Local_mean_time
• Kwpolska 2y ago
  > Yeah, this stuff is weird, but only finitely so, because ultimately a computer’s gotta implement them Historic data can be recorded. Rules like "last Sunday in October" or "first day of Ramadan" can be implemented and handled automatically (even if the current Unix implementations don’t do non-Gregorian calendars out-of-the-box). But there can be time zones whose DST rules are "if the groundhog sees its shadow, we start DST two weeks later, otherwise, there is no DST this year". Some countries actually implement this, except the groundhog is replaced by your friendly local regime.
• bdmatatu 2y ago
  > It’s not like programming languages support representing 61-second minutes anyway Raku supports leap seconds. see https://docs.raku.org/type/Instant https://docs.raku.org/type/Instant
• gausswho 2y ago
  Excellent read around the acrobatics of timezone software. It really is quite flexible. It leads me to wonder. If it's all just an automated and finite offset, there's no reason for daylight savings policies to hew to 60 minutes adjustments. Couldn't a nation decide to have a continuously changing offset throughout the year? It might make their offset lookup table substantially longer, but this could 'solve' daylight savings time It'd be adjusting all the time and you wouldn't notice, just you don't notice when leap seconds occur. Those who rely on analog clocks might no longer adjust the same direction each time!
  • deleted 2y ago
    [deleted]
  • lazide 2y ago
    Please don’t give them any ideas.
  • fragmede 2y ago
    India is UYC+5:30, and doesn't do daylights savings time, which is interesting for interacting with the rest of the world. Of course, China famously has one time zone despite being really wide which makes things interesting both internally and externally.
    • em500 2y ago
      Most of the world doesn't do DST either[1], nowadays it's mostly a European/American thing. [1] See the map at https://en.wikipedia.org/wiki/Daylight_saving_time_by_country# https://en.wikipedia.org/wiki/Daylight_saving_time_by_countr...
  • Gormo 2y ago
    The logical conclusion of going down that route would be to dispense with the concept of time zones altogether, and just revert to using local solar time.
    • crazygringo 2y ago
• deleted 2y ago
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• ochrist 2y ago
  The article says that "Nuuk is in Greenland, and is part of the greater EU cinematic universe." It is correct that Greenland is part of Denmark, and Denmark is a member of EU. But Greenland voted several years ago to stay out of the EU.
  • dmd 2y ago
    Which is why it's part of the greater universe, not the regular one.
    • armada651 2y ago
      Greenland is one of those spin-off movies that is part of the cinematic universe, but is generally considered to be non-canon.
    • IggleSniggle 2y ago
      Like how Spider-Man actually belongs to Sony, not Marvel, and it gets loaned back to Marvel? Or more like how Blade isn't part of the MCU, but totally belongs to Marvel?
      • ta1243 2y ago
        Except Blade is part of the MCu now since Deadpool 3 But I think the analogy may be being stretched
        • IggleSniggle 2y ago
          Ahh, figures. As soon as I said it I thought it likely that Marvel had roped it in at some point. Nothing is safe! Just wait til we get Star-Lord (Guardians of the Galaxy) accidentally facing off against some Jedi just so a writer can make some "Hans shot first" "inside" joke in some "way overshot the time travel to long ago in a galaxy far far away" plot...basically a movie to set up the joke in a trailer.
          • 2y ago
• IgorPartola 2y ago
  I know this is a popular sentiment here but it bears repeating: timezones need to go away. Time according to timezones measures the position of the sun. Except when we clearly decide with daylight savings time that we don’t care about the position of the sun, we just want it to be a certain time. When the sun is directly over NYC it is usually 1pm or 2pm, depending on time of year, but 5pm or 6pm in London. Why? Are these events happening at different times? No, they are happening at the same time. Why do we use a different number for them? Your “time zone” may decide that generally the workday is from 14:00 to 22:00. Why not? We already have second and third shift workers, so the idea of 9-5 is dead anyways. When I schedule a meeting with someone in Tokyo and I am in NYC, is the meeting not happening at the same time? Wouldn’t it be easier to say “let’s do it at 13:00”? We still would need to figure out if people are awake and at work but we have to do that now while also figuring out daylight savings, so not only time but day of the year matters. Heaven forbid you schedule a meeting or an event or a delivery or a stock trade and your time zone gets helpfully updated after you schedule the thing but before it happens. Better hope all the processes and software get that right or else! And here is my favorite example I recently encountered: what is the speed of federal laws in the US? Say the tax brackets are rewritten for 2025, starting “January 1”. Cool, so if you work the NYE shift from 8pm to 4am in Chicago, is it the DC timezone that matters for your taxes? The local? If cannabis is legalized starting at midnight but you get arrested for possession at 11pm the day before in LA are you wrongfully detained or did you miss it by one hour? Timezones are 19th century thinking. We can do better.
  • coldpie 2y ago
    Nah. Any solution you come up with that accounts for how humans actually use time will just reinvent time zones. Could they be more cleanly specified than they are? Sure. But that's just an artifact of grandfathering in historical practices.
    • IgorPartola 2y ago
      See my reply to a parallel comment.
      • 2y ago
• gorgoiler 2y ago
  It seems like it would be so much easier to ship the tzdb algorithm as a single C library that could do arbitrary computation. Instead, the authors prefer to use their own domain language — source files with a compiler to a binary format with a reference parser implementation. The thrust of this article is that’s mostly good enough but their domain language doesn’t include lunar information. The downside would be size and runtime efficiency. I’m guessing tzdata is built the way it is so that it can be extremely small and efficient rather than large and, computationally speaking, comprehensive. You can run it on an Arm M0 as well as an Apple M2.
  • kccqzy 2y ago
    A lot of people appreciate the fact that whenever some random government decides to change of rule of their timezone (such as announcing DST changes), they only get a file update where the file is not powerful enough to be Turing complete instead of a C library update.
    • gorgoiler 2y ago
      That’s a great point. For me though, these updates come via the same OS vendor channels that provided updated binaries too, so it’s not like I’m dodging a recompile.
• fokker 2y ago
  A fun read! My brother actually lives on Lord Howe Island along with his wife and 2 daughters. I’m visiting them in a few weeks too actually. I will share this tidbit with them haha.
• gonzo41 2y ago
  I lived in Hobart for a while and I was a firm proponent of having a Tassie south timezone that had a 2 hour winter shift to get some afternoon light. That six week pit in winter when the sun goes down at 430pm is tough.
• rswail 2y ago
  For years I've been saying that a programming course is composed of two subjects: 1. Date and Time Programming 2. Debugging You will encounter every possible issue and common bug when doing #1, leading naturally to #2.
• twojastara 2y ago
  GUWNO JEBANE
• grishka 2y ago
  Another fun fact about timezones: if the government abolishes DST one year, and then moves some timezones an hour the next year, it creates a wild mess. Especially when you're building an Android app. Especially when it's the early 2010s so the timezone database is built into the system image but most devices that run your app don't receive system updates at all. Instead of picking the timezone with the correct offset and no DST, many people would adjust the time itself so the wrong timezone and the wrong unixtime cancel each other out so the clock "looks right". Not fun when you're doing math with timestamps, some of which are local and some come from the server.
  • jandrese 2y ago
    I worked with a group of people once who just didn't care about timezones. All (ok, most) clocks were set to local time, but with some random timezone, about half of the time it was GMT, and 2/3 of the remainder were our actual timezone, but the rest were totally random. I had to write a "figure out what the time actually is" routine in my code because it was such a pervasive problem.
    • grishka 2y ago
      I ended up doing kinda the same. Our API already had a method to retrieve the current unixtime on the server, which I used, together with the user-set timezone, to figure out the UTC offset that the user actually meant to set by adjusting their clock.
  • lxgr 2y ago
    This makes me wonder: Should NTP servers broadcast the tz database...? (And should the tz database support a stable but turing-complete scripting/bytecode language?)
    • ironmagma 2y ago
      That sounds like the beginning of a story that ends with an RCE.
• Aidevah 2y ago
  > Unless you’re doing some fairly exotic things where you’re finding yourself saying things like >> Oh yeah the OCR on Japanese driving licenses pops out things like “平成 8”, that’s just how they sometimes say 1996 over there. That’s why we have this in the parser: eras = { "大正": 1912, "昭和": 1926, "平成": 1989 } >> One of these days we’ll need to add "令和": 2019, but it hasn’t come up yet. Taiwan also uses the ROC calendar[1] which is directly descended from the regnal calendars of imperial china. But it's quaint that the Japanese name their year after one person, while us enlightened westerners simply use a calendar where it's simply the 2024th year of the, erm, hmmmph... [1] https://en.wikipedia.org/wiki/Republic_of_China_calendar https://en.wikipedia.org/wiki/Republic_of_China_calendar
• sebastialonso 2y ago
  Related to the subject, can anyone recommend a book about timezones? Not a technical, programming book, but one with the history of time zones and curious use cases?
  • noleary 2y ago
    It is not exactly what you're looking for, but long ago I read this book about the invention of the naval chronometer: https://en.m.wikipedia.org/wiki/Longitude_(book) https://en.m.wikipedia.org/wiki/Longitude_(book) It's generally pretty well-regarded and closely related.
    • wbl 2y ago
      Revolution in Time is drier but still interesting and covers up past the quartz crisis starting from Babylon.
    • sebastialonso 2y ago
      Thanks a lot!
• lokar 2y ago
  I recall working on some calendar software and finding that at some point in the past (you have to deal with all the rules from the past) a country (Saudi Arabia?) had an offset like every day to keep solar noon in line with civil time.
• Tepix 2y ago
  I'd like to know the rationale behind these weird timezones, in particular non-hourly offsets to UTC. Why was it chosen that way? Why is it being upheld? It must be a big hassle. Why not switch to a normal 60 minute offset to UTC?
  • ucarion 2y ago
    tzdb often has the answer, and it's almost always because everyone used to do local solar time (i.e. on average, the sun is at the top of the sky at noon) until convenience (i.e. train and plane schedules) required an offset friendlier to mental math.
• pvaldes 2y ago
  With the weirdest inhabitants like the legendary Lord Howe Island stick insect, AKA tree lobsters or more informally sausages with legs. A 20 cm long halloweenesque black beauty.
• 0xbadcafebee 2y ago
  Ever since I was assigned to work on the school website's calendar when I was in high school, I have successfully avoided any software project having to do with time and date. I feel like my quality of life has been better for it.
• danielvaughn 2y ago
  Just wait until we decide on a time zone for the moon, or Mars.
  • perlgeek 2y ago
    Mars days are longer than Earth days, so a time zone alone won't do. I think I actually heard on a podcast that some Mars rover mission team had to operate in shifts that were synchronized with Mars days.
• ak217 2y ago
  At some point the correct solution is for engineers to collectively agree to refuse to model government-prescribed deviations from convention. Or, put more obliquely, provide more feedback to make it more obvious who is bearing the cost of the complexity of these requirements. It's a social problem and it calls for a social solution. I know, there's a lot of disagreement around where the point in question is, but it would serve us well if more engineers were more assertive about stating their opinion on where it is.
  • booleandilemma 2y ago
    This sounds good until you realize that half or more of the software engineers are people working in 3rd world countries who just need a job, or they're H-1B's working in the US who can't afford to make waves. We would need to form some kind of global union and push back together.
    • ak217 2y ago
      In the US there is a great example of a government agency that works to reduce emergent complexity in situations like this - NIST. NIST does a lot of work behind the scenes in advanced technical fields. I wonder if it would help if there was a NIST publication enumerating common time and date keeping patterns, like we have for cryptography.
  • bcherry 2y ago
    disagree - good products meet their users where they are and bury complexity under the hood. i can't imagine trying to use a calendar app (or any app really) that refuses to operate in any mode other than UTC.
    • ak217 2y ago
      OK but most people would agree that "only UTC" is not an ergonomic default. There is a balance. Also, are the users where they are because they want to be there, or because long ago some government or religious leader forced something through and they go along with it because of some kind of inertia?
• heironimus 2y ago
  Me: This does not look interesting at all, but its really popular, so I'll quickly skim it. Me, 5 mins later: I can't stop reading this!
• an-allen 2y ago
  Obligatory - David Olsen and Paul Eggert - thank you for your service. The world literally works because of your efforts and I don’t feel people really appreciate the ridiculous man made problem that you spent your labours to help resolve. If there was a Hall of Fame of OSS contributors - you would be in it sitting on top of a mountain. The Time Zone problem is a unique problem in that its not just a problem of whats the time in this location - its what was the time in this location 20, 50, 100 years ago. The level of scholarship and historical research you put into this library is really quite unmatched. Amazing folks you two. The whole world quite literally sits on the shoulders of you two giants. “Daylight Saving Time was first suggested as a joke by Benjamin Franklin in his whimsical essay “An Economical Project for Diminishing the Cost of Light” published in the Journal de Paris (1784-04-26). Not everyone is happy with the results.” - Paul Eggert
• Lance_ET_Compte 2y ago
  A thousand years ago, every village had their own timekeeping and it worked. Our village is now earth. What if we just abandoned daylight-savings time and timezones and just went with GMT (or anything else) for everywhere on earth? There would be cultural effects as people in California now start work at 16:00, for example...
  • fermuch 2y ago
    Isn't that how china works? One timezone for everyone
    • ianburrell 2y ago
      That is good example why one timezone doesn't work. The locals in Xinjiang use a local time zone +6, instead of China time +8, because the latter is too far off the daylight hours. My understanding is that use of Xinjiang time has dropped recently because of the crack down on Uygurs and government forcing China time.
    • a57721 2y ago
      There are various countries that optimize the number of time zones for administrative purposes, but this is much easier and sensical to implement within one country than globally. UTC is used globally when it makes sense, e.g. for the schedules of international radio broadcasts.
  • chanandler_bong 2y ago
    This. 100%.
  • cle 2y ago
    The hard part is not doing it, it's getting people to agree. I highly doubt people will agree to do that, because a large portion of people don't agree with "our village is now Earth".
    • tshaddox 2y ago
      In order to do computing involving time zones you also need to get an enormous number of people (particularly vendors of computer operating systems and maintainers of programming languages) to agree. But yes, this does appear to be easier than getting a few hundred political jurisdictions to agree.
• chikere232 2y ago
  At some point, adding software support for these things is just enabling bad ideas. If there wasn't support for Australia/Lord_Howe they might be annoyed into picking a simpler time zone
• jmbwell 2y ago
  Those interested in this kind of pedantry might also take care to note that it’s called “daylight saving time,” with no “s.” It is a system of time for saving daylight. It is not a sales event promising “savings.” Frustrating to read an otherwise excellent and detailed article that makes this error throughout.
  • zokier 2y ago
    Both forms are widely used and accepted. Wikipedia has whole section about that: https://en.wikipedia.org/wiki/Daylight_saving_time#Terminology https://en.wikipedia.org/wiki/Daylight_saving_time#Terminolo...
    • jmbwell 2y ago
      Thanks at least for citing a reference and not just saying “language evolves” or something.
• kccqzy 2y ago
  The most amusing tidbit about the tz database is that it contains an estimate of Big Bang, and it refuses to calculate timezone transitions occurring before the Big Bang. The commit message at https://github.com/eggert/tz/commit/b22d459a367f4d01b10f6f6b4e45c2831fc4e2aa https://github.com/eggert/tz/commit/b22d459a367f4d01b10f6f6b... says: > For example, Glib computes Sao Paulo time stamps as if Brazil's circa-1913 rules were still in effect. (Thanks to Leonardo Chiquitto for reporting the bug.) Work around the bug by not generating time stamps equal to -2**63. Come to think of it, time stamps before the Big Bang are physically suspect anyway, so don't generate time stamps before the Big Bang. Soon afterwards, a separate commit disallowed leap seconds before the Big Bang.
  • ucarion 2y ago
    This is really neat! Separately, I'm a little skeptical of the tzdb's endeavor of even thinking about pre-Unix-epoch stuff. The bug-to-utility ratio of that stuff doesn't seem to be there. `zic` is where most of the ugly gnarliness of tzdb lies, and I sometimes feel that it would have been better if `zic` weren't an artifact others could depend on.
    • derefr 2y ago
      There are plenty of people alive today with negative birth timestamps, with many services wanting to calculate the proper local day and time each year to send them annoying pseudo-personalized birthday messages. Or, for something a bit more agreeable: genealogy (esp. the bioinformatics queries in genetic genealogy) needs a good, high-resolution timeline to normalize events onto. Actually, the non-genetic kind of geneaology, solves a lot of vagueries in lineage as constraint-based puzzles over (local!) dates, with razor-thin margins that would be messed up without correct timezone-based calendar conversion — constraints like "two people couldn't have been related as mother and child, if the mother died at least two days before the child was born."
  • eikenberry 2y ago
    That's a fun easter egg in the TZ database. I'd never heard of it, but how often do you need to calculate TZ data that old. Hopefully we'll be done with time zone's completely before the theory is outdated.
• mayneack 2y ago
  My personal favorite timezones: There's UTC+14 in Micronesia: https://en.wikipedia.org/wiki/UTC%2B14:00 https://en.wikipedia.org/wiki/UTC%2B14:00 Also Antarctica/Troll: A timezone for a norwegian research station. https://en.wikipedia.org/wiki/Time_in_Norway https://en.wikipedia.org/wiki/Time_in_Norway
• NotYourLawyer 2y ago
  I’m so glad I don’t have to think about this stuff for my day job. Just miserable.
• autarch 2y ago
  > It’s not like programming languages support representing 61-second minutes anyway This is not true. Someone already noted that Raku supports leap seconds. I think this may be partly my fault, because Perl 5's most popular datetime library, `DateTime.pm`, supports leap seconds. It's my fault because I created `DateTime.pm` and implemented its leap seconds support. In retrospect, this was almost certainly a mistake. Almost no one cares about leap seconds. It just produces all sorts of weird confusion. Like why does adding 60 seconds produce a different result than adding 1 minute, but only rarely? And it makes the code _way_ more complicated, especially since I wanted to validate whether setting second to 60 was valid. This seems simple. Why not just look up the leap second table and check? Well, the `DateTime` constructor takes time components (including `second => 60`) and _any_ time zone. So we have to convert the date/time passed to the constructor to UTC in order to do that lookup. But doing that conversion ... ended up involving values that include leap seconds because of historical reasons. It's a huge mess for very little gain. As to Raku, I think it's stdlib datetime library borrowed from Perl 5's `DateTime.pm` quite heavily so it inherits some of the same bad design decisions.
  • Loughla 2y ago
    I like that you did it and can look back with a more elegant solution. What was the thought process originally? Were you just too focused on the problem? I find that if I'm too close to the problem and too focused for [arbitrary timeframe], this is the type of thing that happens. The joy of fixing something before it's broken takes over.
    • autarch 2y ago
      I wrote this code in the early 2000s, so I don't remember the exact thought process. But I think my thinking was something along the lines of "this is a thing that exists, therefore I should model it 100% accurately". But I think the right way to think about it is "this is a thing that exists but most developers would be better off never thinking about, therefore I should omit it entirely". Of course, the _real_ correct solution is to split up a date/time library into a number of closely related classes/structs, and allow users to pick the one that meets their needs. So most folks would pick the leap second-free class, but a few would use the one with leap seconds baked in.
• 0x70dd 2y ago
  Correctly ingesting and visualizing data that's captured by different devices while also accounting for travel across timezones, is a real challenge. [1] is our guide how we do this for diabetes data generated by CGMs and insulin pumps. [1] https://tidepool.stoplight.io/docs/tidepool-api/branches/master/1da4b594ec557-date-time-guide https://tidepool.stoplight.io/docs/tidepool-api/branches/mas...
• tdeck 2y ago
  > Morocco and Gaza do their daylight savings based on Ramadan. Something about this doesn't make sense. My understanding is that Ramadan can happen at any season of the year (imagine fasting all day in Greenland during the summer!) because the Islamic calendar doesn't insert intercalary months like many other "lunar" calendars do. Given that, what is the benefit of having a daylight savings time at all if it's tied to the lunar calendar? Isn't the idea of DST tied to day length?
• krick 2y ago
  The most interesting (perhaps, the only truly interesting) thing in this writeup is his `tzdump` script. I checked his github, and it seems he didn't share it anywhere, unfortunately.
• rodarmor 2y ago
  The best example of managing expectations of all time is in the Time Zone Database documentation: > The tz database predicts future timestamps, and current predictions will be incorrect after future governments change the rules.
• leshenka 2y ago
  I absolutely love how this is written and hate how mouse cursor doesn't turn into pointer when hovering above links.
• niemandhier 2y ago
  I love the zone Europe/Busingen. Büdingen has about 1500 inhabitants.
• dublin 2y ago
  Despite having 4 of the 10 largest cities in the US, no Texas (or other Southern) city rates a listing in the zoneinfo file, so we're stuck having to pick Chicago, which is so far away (~1000 miles from Austin, in the middle of the state), that many people in the Southern US aren't necessarily certain what timezone Chicago is even in. (The #10 slot varies according to source, but in general, Houston #4, San Antonio #7, Dallas #9, Austin #10. Fort Worth is nearly tied with Austin. Some sources claim Jacksonville, FL is #10, but they must be wrong...) :-)
• Tepix 2y ago
  Has there been any serious research regarding having a better calendar and time? We're pretty much stuck with 365.25 days per year i guess, but other than that... the one thing that's obvious is that currently it's overly complex.