Infinite Undo
infiniteundo.com · Personal blog · on HN since 2012
Software engineer Noah Sussman writes about testing, software as narrative, and the 'Falsehoods programmers believe about time' essay.
What HN saysHN commenters repeatedly link the classic 'Falsehoods programmers believe about time' post and its follow-up whenever time handling comes up.
89HN people shared it
66linked it in comments
40stories submitted
928story points
8 months agolast shared
2012people per year2026
Most-shared posts
- 1Falsehoods Programmers believe about Time71 people · 766 points · first shared 2012 · 213 comments on HN
- 2More Falsehoods Programmers Believe About Time (2012)20 people · 22 points · first shared 2015 · 4 comments on HN
- 3More falsehoods programmers believe about time5 people · 3 points · first shared 2012 · discussion on HN
- 4108 Counterintuitive Things About Testing2 people · 6 points · first shared 2017 · 1 comments on HN
- 5Software is narrative1 people · 92 points · first shared 2017 · 41 comments on HN
- 6Help the Lawyers are teaching lawyers to use Twitter as a first-responder tool1 people · 6 points · first shared 2017 · discussion on HN
- 7100 Counterintuitive Things About Testing by the Author of Falsehoods About Time1 people · 4 points · first shared 2017 · 11 comments on HN
- 8Etsy's former Test Arcthitect wrote up 13 howtos on dev environment lifehacks1 people · 4 points · first shared 2017 · discussion on HN
- 9Code coverage: What is the goal?1 people · 3 points · first shared 2014 · discussion on HN
- 10The way tech manages workers runs counter to all current science on productivity1 people · 3 points · first shared 2017 · discussion on HN
- 11Devops sketchbook by noah the etsy pipeline architect1 people · 2 points · first shared 2017 · discussion on HN
- 12Etsy's original training deck on software defects1 people · 2 points · first shared 2017 · discussion on HN
- 13“The Rule of Three” is a TERRIBLE strategy for code refactoring / reuse1 people · 2 points · first shared 2017 · discussion on HN
- 14Someone just invented the killer app for lawyers at airports1 people · 2 points · first shared 2017 · discussion on HN
- 1510 Tired Trends In Software Testing Discourse1 people · 2 points · first shared 2016 · 2 comments on HN
What HN people wrote when they linked it
noahlt · 2025-11-12
He’s referencing this classic blog post: https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
Discussed on HN here: https://news.ycombinator.com/item?id=32548085
vladde · 2025-02-19
… and the follow-up: https://infiniteundo.com/post/25509354022/more-falsehoods-programmers-…
gvv · 2021-11-08
Good followup on falsehoods about time https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
grenoire · 2021-01-03
Hitting up the classic article, https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
robin_reala · 2020-09-25
Appropriate to link to the classic “Falsehoods programmers believe about time” here: https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
JdeBP · 2019-03-06
The "S" stands for "Summer", and I strongly recommend reading things like https://infiniteundo.com/post/25509354022/more-falsehoods-programmers-… and http://creativedeletion.com/2015/01/28/falsehoods-programmers-date-tim… before confidently making statements on this subject.
dmitrygr · 2018-12-26
As always, the 2-part "Falsehoods programmers believe about time" is a good read:
https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
https://infiniteundo.com/post/25509354022/more-falsehoods-programmers-…
lloeki · 2018-09-21
There's a follow-up: https://infiniteundo.com/post/25509354022/more-falsehoods-programmers-…
ryandrake · 2016-09-04
I love the "Falsehoods programmers believe about X" articles. They are basically ready-made failure test cases. Whenever a junior co-worker would say something like "I know! I'll just write our own date and time handling code." I'd point him at [1], let him stew on that for an hour or so, and then, sure enough, go back and lo and behold he's convinced to just use a ready-made third party library instead.
1: http://infiniteundo.com/post/25326999628/falsehoods-programmers-believ…
fragmede · 2016-08-17
Past bikeshedding, there's also the long list of myths programmers believe about time[1] and the crowd-sourced followup[2]. Pendulum inherits from datetime in the stdlib, but I'm unsure how well either of those address the issues raised (or even if it's possible - some need to be addressed by the code that uses pendulum/datetime).
[1] http://infiniteundo.com/post/25326999628/falsehoods-programmers-believ…
[2] http://infiniteundo.com/post/25509354022/more-falsehoods-programmers-b…
Schwolop · 2015-08-21
Absolutely agree with the "one of those assumptions" bit. See http://infiniteundo.com/post/25326999628/falsehoods-programmers-believ… for a great list.
(And related, see https://www.mjt.me.uk/posts/falsehoods-programmers-believe-about-addre… for more about addresses.)
mdaniel · 2025-04-13
https://dev.arie.bovenberg.net/blog/python-datetime-pitfalls/#5-guessi… highlighted yet another thing that I hadn't previously considered and makes me plug <https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie… <https://news.ycombinator.com/item?id=4128208>
EGreg · 2024-09-14
I saw this one first, but seems patio11 was first:
https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
mrngm · 2024-03-27
Always good in these kind of time-related situations to dig up https://news.ycombinator.com/item?id=4128208 which links to "Falsehoods programmers believe about Time": https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
whoisthemachine · 2023-06-26
Evergreen article that neatly lists the problems with time (not just as a version key): https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
dfee · 2022-12-31
Came here looking for a comment suggesting these discrepancies. I was not disappointed.
See also: “Falsehoods programmers believe about time”
https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
epgui · 2022-10-09
Examples of essential complexity you have to worry about if you want your code to be correct, and even if you want to test/detect all issues that can/do come up:
- https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
- https://infiniteundo.com/post/25509354022/more-falsehoods-programmers-…
In my experience engineers will often brush these sorts of things off as “edge cases”, but really all of these complexities are just how dates and time work in the real life (I’d argue that they’re just “normal cases” to test for)… So any anomaly in software will cause real problems of varying importance for users.
pigbearpig · 2022-08-22
Should the link be updated to the actual source? This gist appears to just be a copy of https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie… and https://infiniteundo.com/post/25509354022/more-falsehoods-programmers-…
https://gist.github.com/timvisee/fcda9bbdff88d45cc9061606b4b923ca#sour…
Hussell · 2022-03-17
For those who haven't seen this before, the ones you should look at first are:
Falsehoods about Names https://www.kalzumeus.com/2010/06/17/falsehoods-programmers-believe-ab…
Falsehoods about Time https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
Falsehoods about Addresses https://www.mjt.me.uk/posts/falsehoods-programmers-believe-about-addre…
alanbernstein · 2022-03-16
Needs to write what? https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie… ?
clusterfish · 2022-02-08
I'm not sure if this is the original, but here: https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
npongratz · 2022-01-13
We already do: https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
HN discussion (among others less recent and/or less popular): https://news.ycombinator.com/item?id=19922062
More falsehoods: https://infiniteundo.com/post/25509354022/more-falsehoods-programmers-…
boondaburrah · 2022-01-04
ho boy, before I break out "falsehoods programmers believe about time,"[0] nobody wants to manually have to rewrite the UTC time something's supposed to run at when the business hours keep changing relative to UTC for (at the most basic) Daylight Savings reasons.
[0] https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
(if this is your first time seeing this article, have fun! also check out the one about names.)
zbentley · 2022-01-01
Time to trot this out again: https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
humanistbot · 2021-08-06
> It makes me angry that programmers feel that they "own" the concept of time measurement
Programmers feel that they "own" pretty much every social construct, by virtue of the fact that it is their job to encode those constructs into interfaces and databases. See the famous "falsehoods programmers believe about X" [1] --- and I'm sure you'll like this one about time [2].
[1] https://github.com/kdeldycke/awesome-falsehood
[2] https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
peterburkimsher · 2020-10-20
https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
I'm very thankful for the creators of https://www.worldtimebuddy.com/ handling time zone weirdness, etc, so that I can still get to Zoom calls on time (usually). I don't know how the Moment developers can ever think it's "done" - "We now generally consider Moment to be a legacy project in maintenance mode. It is not dead, but it is indeed done."
csunbird · 2020-05-15
egeozcan · 2020-03-11
Me, a 13 years old kid who was experimenting with QBASIC in 1999, thought that it was just switching from LEFT$(x, 2) to LEFT$(x, 4) when parsing dates. I still chuckle when I think how massively I had underestimated that problem.
Meanwhile, the industry still doesn't know how to deal with dates and times correctly: https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
jmcqk6 · 2020-03-01
I"m just going to leave this here: https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…
carapace · 2020-02-17
That's a can of hairy worms right there.
Check out "Falsehoods programmers believe about time": https://infiniteundo.com/post/25326999628/falsehoods-programmers-belie…