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staplung commented on Boston's subway system replacing 1890s-era wooden catenary system   mbta.com/news/2025-11-18/... · Posted by u/ilamont
jpmattia · 12 days ago
Hold a chain at its ends, and let it hang down naturally. What is that shape called? A catenary and its equation is y = a cosh(x/a).

Maybe you all knew that factoid already, but I learned the name of shape only recently.

staplung · 12 days ago
I actually did already know that factoid but was struggling (am still) to see how it relates to a wooden trough that merely holds cables.

Another interesting factoid about the catenary: Robert Hooke proved that it takes on the shape (though inverted) of the ideal arch, in terms of supporting loads above it. La Sagrada Familia in Barcelona is filled with them.

staplung commented on Is C++26 getting destructive move semantics?   stackoverflow.com/questio... · Posted by u/signa11
staplung · 25 days ago
Sounds like the answer is no.

"For trivial relocatability, we found a showstopper bug that the group decided could not be fixed in time for C++26, so the strong consensus was to remove this feature from C++26."

[https://herbsutter.com/2025/11/10/trip-report-november-2025-...]

staplung commented on Microsoft makes Zork open-source   opensource.microsoft.com/... · Posted by u/tabletcorry
drob518 · 25 days ago
I’m curious why they chose MDL rather than Lisp for it. Sure, it would have been ancient MACLISP or whatever, but why not leverage what was already in wide use at MIT at the time?
staplung · 25 days ago
MDL is also from MIT and supposedly stood for More Datatypes than Lisp. According to wikipedia "MDL provides several enhancements to classic Lisp. It supports several built-in data types, including lists, strings and arrays, and user-defined data types. It offers multithreaded expression evaluation and coroutines."

Seems that most of it's novelties were eventually added into LISP proper.

staplung commented on CRDTs: Convergence without coordination   read.thecoder.cafe/p/crdt... · Posted by u/0xKelsey
cbm-vic-20 · 2 months ago
The article sets up a scenario where two people are editing a document, but have conflicting changes: "If Alice fixes a missing letter in a word while Bob removes the whole word, that’s a conflict."

The article then goes into some examples of CRDTs and their merge operation, and the examples are pretty straightforward: take the maximum of two values, or take one with a more recent timestamp, etc.

But what about the motivating example? What should a merge function do with the inputs "change the third word from 'affect' to 'effect'" and "delete the third word"? In other words, how does the function know which of these operations "wins"? It could ask a user for a manual resolution, but is there a reasonable way for a function to make this determination itself? Maybe deletes are more powerful than word changes, so the delete wins.

staplung · 2 months ago
The "conflict-free" part of the name is misleading. The conflict "resolution" means having some deterministic algorithm such that all nodes eventually converge to the same state, but it won't necessarily mean that the end state looks like it's conflict-free to a human. The algorithm you choose to implement will determine what happens in the editing case imagined; various answers are possible, perhaps most of which would be classified as conflicting changes by a human who looked at the final result. The pitch for CRDTs is "we won't trouble you with the replication details and will eventually converge all the changes. The tradeoff is that sometimes we'll do the wrong thing."

That tradeoff is fine for some things but not others. There's a reason why git et al require human intervention for merge conflicts.

The article is doing a classic bait-and-switch: start with a motivating example then dodge the original question without pointing out that CRDTs may be a very bad choice for collaborative editing. E.g. maybe it's bad for code and legalese but fine for company-issued blog posts.

staplung commented on Show HN: I've built a tiny hand-held keyboard   github.com/mafik/keyer... · Posted by u/mafik
staplung · 2 months ago
Totally rad.

Now you just need and Oculus and you can turn yourself into Johnny Mnemonic.

https://www.youtube.com/watch?v=UzRjtvMQds4&t=63s

staplung commented on A few things to know before stealing my 914 (2022)   hagerty.com/media/advice/... · Posted by u/visviva
wingspar · 2 months ago
“ Since there is not a clutch safety switch on the starting circuit, make sure to press the clutch down before you try to crank the engine.”

Growing up, a friends dad would use this as a ‘feature’ on his Datsun to move the car out of traffic when it wouldn’t restart.

Put it in first, release the clutch, crank the starter, and move the car out of the way.

staplung · 2 months ago
"Driving" via the starter motor turns it into an electric car!
staplung commented on Ants trapped in a Soviet nuclear bunker survived for years (2019)   sciencealert.com/ants-tra... · Posted by u/MaysonL
staplung · 2 months ago
"Difficult to tell from this vantage point if they will consume the captive Earth-men or merely enslave them...one thing is for certain: there is no stopping them; the ants will soon be here! And I for one welcome our new insect overlords. Like to remind them that as a trusted TV personality I could be helpful in rounding up others to toil in their underground sugar-caves."

https://www.youtube.com/watch?v=W4jWAwUb63c

staplung commented on Norway to monitor airborne radioactivity in Svalbard   highnorthnews.com/en/norw... · Posted by u/bookofjoe
kjkjadksj · 3 months ago
They did have ways to detect nuclear incidents before then. Vela satellites for example. They seem to have been more tuned for detecting nuclear bombs vs generalized fallout however. Maybe others can speak more towards this.
staplung · 3 months ago
The last of the Vela satellites were shut down in 1984 or 1985 (I've found conflicting sources on this) but in any case, before Chernobyl (April, 1986). They were replaced by other systems of course but as others have pointed out, those were never designed to detect fallout. Bhangmeters look for a characteristic double-flash of light from atmospheric nuclear detonations.
staplung commented on Norway to monitor airborne radioactivity in Svalbard   highnorthnews.com/en/norw... · Posted by u/bookofjoe
staplung · 3 months ago
It's interesting to note how the West discovered there had been a nuclear accident in the USSR when Chernobyl exploded. The Forsmark reactor in Sweden detected the fallout on the clothing of workers returning to the plant after lunch, IIRC.

Surprised this station seems to post-date that? Seems like it would have been handy to have in the Cold War. Then again, Russia has long had a mining presence on Svalbard so maybe that has something to do with it.

u/staplung

KarmaCake day1688June 10, 2014
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Software Engineer in SF.
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