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Nura (PostmarketOS): The road to daily-drivable mainline phones

https://nura.eco/blog/2026/09/29/road-to-main-category/
1•birdculture•47s ago•0 comments

Five ways publishers are rethinking audience engagement

https://www.niemanlab.org/2026/09/how-publishers-are-rethinking-audience-engagement-five-takeaway...
1•giuliomagnifico•1m ago•0 comments

Financing the AI Buildout

https://www.brookings.edu/articles/financing-the-ai-buildout/
1•dgellow•2m ago•1 comments

Snapdragon Sound Elite Gen 2

https://www.qualcomm.com/audio/products/snapdragon-sound-elite-gen-2
1•ksec•2m ago•0 comments

A laser just photographed objects through six feet of concrete

https://newatlas.com/technology/pics-muon-laser-reveal-unseeable/
1•geox•2m ago•0 comments

SB&R – Chained Referral Campaign for Online Brands

https://apps.shopify.com/sb-r
1•HMNayak•2m ago•0 comments

RAM supply set to worsen, says Micron, as CEO celebrates 'much higher' prices

https://www.theregister.com/systems/2026/10/01/ram-supply-set-to-worsen-says-micron-as-ceo-celebr...
1•mdp2021•4m ago•0 comments

Learning Steganography Is Easy, Learning Steganographic Reasoning Is Hard

https://arxiv.org/abs/2609.39838
1•sbulaev•6m ago•0 comments

Clausewitz on Operation Epic Fury

https://www.justsecurity.org/147675/clausewitz-operation-epic-fury/
1•bryanrasmussen•7m ago•0 comments

The Cost of Vibe-Coding Games [video]

https://www.youtube.com/watch?v=5cbonpAgR5A
1•i2talics•7m ago•0 comments

In Search of Northanger Abbey: Farleigh Hungerford Castle

https://englishhistoryauthors.blogspot.com/2026/08/in-search-of-northanger-abbey-farleigh.html
1•bryanrasmussen•7m ago•0 comments

OpenAI halved the allowance of the $200 plan to 10x

2•k9294•8m ago•0 comments

Pebble Round 2 starts shipping

https://repebble.com/blog/pebble-round-2-starts-shipping
1•smig0•8m ago•0 comments

Landon – a lean and easy landing page builder

https://landon.click
1•pathwaysdigital•10m ago•1 comments

By far the best QA automation tool for iOS app?

https://midscenejs.com/
1•danielhitome•10m ago•1 comments

Show HN: A shared world map where every building can be leveled by tank

https://worldstrike.fun/
2•error404x•11m ago•0 comments

A Primer on Rydberg Atom Antennas

https://rfessentials.com/industry-news/quantum-computing/rydberg-atom-antennas-primer/
1•chicken-stew•11m ago•0 comments

What the F*** did that bank do?

https://xlii.space/eng/what-the-f-did-that-bank-do/
1•xlii•12m ago•0 comments

Harness Engineering: Anatomy, Architecture, and Evolution of Coding Agents

https://arxiv.org/abs/2609.00006
1•ghaith123•12m ago•0 comments

Bil Concurrency Distilled

https://bil-lang.org/bil-concurrency-distilled/
1•librasteve•13m ago•1 comments

iOS and macOS CI benchmark: Avrea is 3-23x faster than GitHub Actions

https://avrea.com/blog/ios-macos-ci-benchmark
2•leolannenmaki•14m ago•1 comments

What's Up in Space

https://Spaceweather.com
1•gscott•16m ago•0 comments

Swale – Local first developer assistant

https://www.npmjs.com/package/@itssayantan/swale
1•sayantanghosh-i•19m ago•0 comments

I built a WhatsApp client for Emacs without an API

https://en.andros.dev/blog/782e8f3b/how-i-built-a-whatsapp-client-for-emacs-without-an-api/
1•andros•19m ago•0 comments

A session health and monitoring tool for Codex Desktop

https://github.com/GG95-lab/FreshThread-app
1•shadowsync•22m ago•0 comments

"Google was not the first market leader in internet search. It was Netscape"

https://www.bbc.co.uk/news/articles/cv8e30enrkxyo
1•chrisjj•23m ago•1 comments

Celestial polarization patterns sufficient for Viking navigation with naked eye

https://pmc.ncbi.nlm.nih.gov/articles/PMC5367315/
1•cubefox•24m ago•0 comments

It's World Postcard Daaaaaaaaaaaay

https://www.postcrossing.com/blog/2026/10/01/it-s-world-postcard-daaaaaaaaaaaay
1•Tomte•26m ago•0 comments

A Data Love Letter to the NYC Subway

https://www.pentagram.com/work/a-data-love-letter-to-the-subway
1•benwen•28m ago•0 comments

Almost everyone naturally turns left when walking–and we still have no idea why

https://medicalxpress.com/news/2026-09-naturally-left-idea.html
1•mdp2021•28m ago•0 comments
Open in hackernews

Understanding-j: An introduction to the J programming language that gets to the

https://github.com/bugsbugsbux/understanding-j
62•todsacerdoti•1y ago

Comments

prezjordan•1y ago
To the author: you can add a .devcontainer directory with a Dockerfile, allowing folks to try this in their browser with GitHub Codespaces

Shameless plug, feel free to copy my setup! https://github.com/jdan/try-j

userbinator•1y ago
Unintentional humour with how the title got cut off?
pixelpoet•1y ago
The title stops just short of the
johnisgood•1y ago
"to the point", I presume, based on its README.
pjmlp•1y ago
A side effect of the small length available for titles and the whole titles should not be editoralised point of view.
Jtsummers•1y ago
It's more an issue of todsacerdoti not checking their submission titles will fit, they do this a lot with their submissions. Abbreviating titles is not frowned upon when they don't fit, I've never had any reverted to something like this submission's title because I (for instance) shortened "United States" to "US" to shave off 11 characters.

In this case, cutting out the superfluous "programming language" part would get you "Understanding-j: An introduction to J that gets to the point" which would fit just fine. When in doubt, include the original title in a comment to explain the edit and let the mods sort it out later.

detaro•1y ago
It's hard to check if titles fit if you use a bot to repost from other sites.
Jtsummers•1y ago
Fair, they're lazy and can't be bothered to fix their bot even after 5 years of submitting messed up titles.
t-writescode•1y ago
From the doc,

  _3                  NB. negative numbers start with underscore
  _                   NB. sole underscore is infinity: a number
  __                  NB. negative infinity
Is this a standard I'm unaware of?
avmich•1y ago
The use of underscore for negative numbers is J's choice, explained e.g. here - https://www.jsoftware.com/docs/help807/jforc/preliminaries.h... .

Explicitly representing infinity, and working with it in some cases, allows to reduce number of exceptions...

Avshalom•1y ago
APL used ¯3 for negative 3; J went underscore to be similar but ascii.
gitroom•1y ago
Underscore stuff always throws me off - never quite got used to how J does it. Gotta respect the weird choices though.
jbverschoor•1y ago
Not the same as (Visual) J++. Great IDE btw
vintagedave•1y ago
I’ve recently come to be fascinated by J.

Twenty years ago, studying my computing degree, one semester we learned J. It was unlike anything I’d used before and the entire class found it confusing. The compiler / environment was reportedly written by one of the professors and it was routine to run into bugs; I remember puzzling through something, going to a tutor, and them just shrugging it off as a J interpreter issue. I never grokked it and simply passed the course.

But it keeps on recurring to me and I pause to think of J at the weirdest times. As I use more and more languages, I’ve become more fascinated by it. Just like Prolog (also one semester, but with a reliable environment.) I want to learn both better.

binary132•1y ago
I’ve been thinking for the past couple of years that the ideal programming language would be something like a combination of a concatenative language (a la FORTH) and an array programming language.
gnubison•1y ago
Uiua?
binary132•1y ago
interesting, I have not seen this one
preguntador•1y ago
12j34 is 12j + 34 or 12 + 34j?
quartern•1y ago
12 + 34j as per https://code.jsoftware.com/wiki/Vocabulary/Constants#Complex...