Top all-time · #4025
Lau Taarnskov
Personal blog · creativedeletion.com · on HN as lautprogramming
Lau Taarnskov writes Creative Deletion, a personal blog at creativedeletion.com about programming. Since 2009, 19 different Hacker News readers have linked it 44 times, most often “Falsehoods programmers believe about time and time zones”. The last post was in 2021, but the archive is still widely read.
Too few sampled comments (8) to say how often HN recommends it.?
Why HN links it
HN readers link Lau Taarnskov's posts on date and time pitfalls for programmers, including the falsehoods programmers believe list and advice on storing future appointments across timezone and DST changes.
Summarised by Claude from a sample of 8 HN comments that link here. Each comment is marked recommending, critical or neutral (citing without judging); how this works.
Lau Taarnskov's blog on tech
Most-linked posts?
- Falsehoods programmers believe about time and time zones9 people · 13 mentions · first linked 2015-01-28
- How to save datetimes for future events7 people · 13 mentions · first linked 2015-03-23
- Elixir – The next big language for the web2 people · 2 mentions · first linked 2015-04-20
- Falsehoods programmers believe about time and time zones2 people · 2 mentions · first linked 2015-01-30
What Hacker News says?
I don't think anyone is saying that you shouldn't store datetimes in UTC. It's just that time is complex and the errors can be subtle, and you don't want to mess up appointments across timezones because you didn't factor in the timezone when appointment was originally made. http://www.creativedeletion.com/2015/03/19/persisting_future...
Comment linking /2015/03/19/persisting_future_datetimes.html
on “Things I learnt the hard way in thirty years of software development”Submitted Elixir – The next big language for the web as a story · 155 points
HN discussionThe "S" stands for "Summer", and I strongly recommend reading things like https://infiniteundo.com/post/25509354022/more-falsehoods-pr... and http://creativedeletion.com/2015/01/28/falsehoods-programmer... before confidently making statements on this subject.
Comment linking /2015/01/28/falsehoods-programmers-date-time-zones.html
on “European Parliament set to end EU-wide daylight savings”Submitted Falsehoods programmers believe about time and time zones as a story · 128 points
HN discussionThere is a case to not store a time in UTC: you schedule a meeting in the future and the local authorities change when they start DST in that location. Now your user gets the alert an hour too early or late for their meeting. The scenario is more fleshed out in the link below but I don't want to just copy and paste the article into the comment. http://www.creativedeletion.com/2015/03/19/persisting_future...
Comment linking /2015/03/19/persisting_future_datetimes.html
on “Dates and Times in JavaScript – A New API for Dates from TC39”Submitted How to save datetimes for future events as a story · 89 points
HN discussionAlso: Falsehoods programmers believe about time and time zones: http://www.creativedeletion.com/2015/01/28/falsehoods-progra...
Comment linking /2015/01/28/falsehoods-programmers-date-time-zones.html
on “Falsehoods Programmers Believe About Phone Numbers”Submitted The need for timezone awareness as a story · 52 points
HN discussionThis is kinda depressing reading for the start of the workweek. Also, I wish each of these was more expanded.. I can think of many workarounds for each of these situations but I am curious what other people's solutions might be: http://www.creativedeletion.com/2015/01/28/falsehoods-progra...
Comment linking /2015/01/28/falsehoods-programmers-date-time-zones.html
on “A curated list of falsehoods programmers believe”Submitted Timezone updates need to be fixed as a story · 27 points
HN discussionGovernment monopoly. It's in Australia which has a telco monopoly. Internet is very expensive there. I was there as a tourist and left earlier than planned because it was so hard/expensive to get internet access. In third world countries on the same trip it was easier/cheaper to get internet access than in Australia. Wrote about it here: http://creativedeletion.com/2008/11/05/wifi-in-sydney-availa...
Comment linking /2008/11/05/wifi-in-sydney-available-but-sparse-expensive-restricted/
on “Woman removes SIM card from smart energy meter, uses $193k of 3G data”Submitted Using Elixir instead of cron as a story · 9 points
HN discussionDepending on what you need to do, UTC does not always work: http://www.creativedeletion.com/2015/03/19/persisting_future...
Comment linking /2015/03/19/persisting_future_datetimes.html
on “Falsehoods programmers believe about time and time zones”Submitted Timezone updates need to be fixed as a story · 9 points
HN discussionThey might have more resources, but they also have constraints. For instance a tzdata update was just released yesterday. Apple has a lot of resources but I don't see an updated from them today on iOS nor Mac OS X. Elixir tzdata automatically updates to the new version. Does Apple even have resources that work on tzdata code? Or do they just use open source code? I wrote more about the issue here: http://www.creativ…
Comment linking /2015/12/03/timezone-updates-need-fixing.html
on “Falsehoods programmers believe about time and time zones”Submitted Elixir – The next big language for the web as a story · 7 points
HN discussionUTC can also fail if your users need to see or enter times that are not in UTC. E.g. for a meeting or a train schedule or an appointment etc. See this http://www.creativedeletion.com/2015/03/19/persisting_future...
Comment linking /2015/03/19/persisting_future_datetimes.html
on “Falsehoods programmers believe about time and time zones”Submitted Falsehoods programmers believe about time and time zones as a story · 5 points
HN discussionIf you're writing a calendar app, then you should probably store the triple of `local time`, `time zone name`, `version of time zone database used to look up time zone name` https://codeblog.jonskeet.uk/2019/03/27/storing-utc-is-not-a... and http://www.creativedeletion.com/2015/03/19/persisting_future...
Comment linking /2015/03/19/persisting_future_datetimes.html
on “The strangest time zones in the world (2015)”Submitted Is Elixir getting more popular in the last year? as a story · 4 points
HN discussionThis post describes examples of ambiguity and non-existing times: http://www.creativedeletion.com/2015/01/28/falsehoods-progra... Note non-existing times mostly happen when you go from winter time to summer time. You set the clock ahead an hour at let's say 2:00 in the morning. So you go directly from 2:00 to 3:00. 2:30 does not exist. So let's say that you plan a meeting at 2:30 in the morning in a country that doe…
Comment linking /2015/01/28/falsehoods-programmers-date-time-zones.html
on “How to save datetimes for future events”Submitted Falsehoods programmers believe about time and time zones (2015) as a story · 3 points
HN discussionRight, it is unambiguous for the current rules and zone. Usually if the rules change, you want to do the calculation again. I made a library for persisting future DateTimes to a database. Whenever a DateTime is loaded from the database, the calculation is done again. A blog post about it can be found at http://www.creativedeletion.com/2015/03/19/persisting_future... If the "borders of the timezones" change, that doe…
Comment linking /2015/03/19/persisting_future_datetimes.html
on “The need for timezone awareness”Submitted Falsehoods programmers believe about time and time zones as a story · 3 points
HN discussionHere is an example where the "convert it to UTC" rule would fail: http://www.creativedeletion.com/2015/03/19/persisting_future... I will stick non-UTC time into the database and I made a library to do it.
Comment linking /2015/03/19/persisting_future_datetimes.html
on “The need for timezone awareness”Submitted How to save datetimes for future events as a story · 2 points
HN discussionIt is a good video. The good thing about using a library like Kalends is that it takes into account everything he mentions about different timezones into account. Just tell it the time, date, and timezone name. Just be careful about generalizing too much and assuming things such as: "this time will exist again tomorrow". Or "next month also has a 31st day". Or "DST is always a 3600 second difference from standard ti…
Comment linking /2015/01/28/falsehoods-programmers-date-time-zones.html
on “The need for timezone awareness”Submitted Data types and assumptions and how incorrect assumptions made a spacecraft crash as a story · 2 points
HN discussionIt’s difficult to maintain basic features in a popular calendar, at least according to the ms exchange team blog: > calendaring is particularly tricky. Why’s that? Well, consider time zones for a start – a meeting you set up isn’t necessarily in the same time as it is for me, and then you also invited people, from a whole bunch of other time zones (did you know some time zones are 30 mins off, not a full hour?) (…)…
Comment linking /2015/01/28/falsehoods-programmers-date-time-zones.html
on “I failed moving my Google calendar to Proton”Submitted Why not to ask the server for its “local time” as a story · 2 points
HN discussion
