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The L.A. people who record random sounds, from duck quacks to fax machines

https://www.latimes.com/lifestyle/story/2026-10-05/los-angeles-field-recording-club
1•rdmuser•57s ago•0 comments

Show HN: Screen Records – edit demo or how-to recordings with MCP

https://screenrecords.app/
1•littlebusywoman•1m ago•0 comments

Thousands of Exposed Systems in Europe's Wind Farms and Solar Parks

https://modat.io/blog/to-see-the-wind-and-the-sun/
1•vanschelven•2m ago•1 comments

Show HN: Plexavo – simplest way to find AWS misconfigurations and attack paths

https://github.com/plexavo/Plexavo
1•kavee-dev•3m ago•0 comments

A Calendar of Smells

https://worldsensorium.com/a-calendar-of-smells/
1•dnetesn•3m ago•0 comments

NewsGuard Launches First AI Chatbot Built to Deliver Trusted Journalism

https://www.newsguardtech.com/press/newsguard-launches-first-ai-chatbot-built-to-deliver-trusted-...
1•bariumbitmap•4m ago•0 comments

- I tried to build a WCAG-friendly iPhone calendar – please prove me wrong

https://testflight.apple.com/join/sKcmUdAq
1•marc0janssen•4m ago•0 comments

The Fossil Logic of the Industrial and AI Revolutions

https://blue-continuum.com/fossil-logic
1•dnetesn•4m ago•0 comments

Chinese Plug-In Hybrid SUV Was UK's Best Selling Car Last Month

https://insideevs.com/news/810819/jaecoo-7-uk-best-selling/
1•bookofjoe•5m ago•0 comments

States Can Cut Rules and Regulations–and Make It Stick Idaho's Two-Step Process

https://manhattan.institute/article/how-states-can-cut-rules-and-regulations-and-make-it-stick
1•djoldman•5m ago•0 comments

Observability Doesn't Have to Be Expensive

https://telemetrymachine.dev/blog/observability-doesnt-have-to-be-expensive
1•tmach32•6m ago•0 comments

Schools must be like gyms

https://www.freddyvega.com/p/schools-must-be-like-gyms
1•marcelo-earth•6m ago•0 comments

Show HN: I'm building an open-source Gong alternative (MIT)

https://github.com/Yz613/Sales-Coach
1•Yehudazahler•7m ago•0 comments

Test Driven Development in the AI Era [pdf]

https://monografias.dcc.ufmg.br/wp-content/uploads/TDD_in_the_AI_Era___POC_2-1.pdf
1•neogodless•9m ago•0 comments

Become Worthless (To Tech Companies)

https://www.coryd.dev/posts/2026/become-worthless-to-tech-companies
1•robin_reala•9m ago•0 comments

Show HN: Tinyhat, per-specialist memory for multi-agent Muse (open source)

https://github.com/tinyhat-ai/muse-office
1•Alireza_kh•10m ago•0 comments

ApowerB: Deploy on Kubernetes using helm-chart

https://artifacthub.io/packages/helm/apowerb/apowerb-chart
4•faridovski•10m ago•4 comments

Fede's Guide to a Healthier Life

https://federicocarrone.com/articles/health-guide/
1•wslh•12m ago•0 comments

TikTok Video Reels for PC

https://chromewebstore.google.com/detail/empty-title/peejbgcjjdmgladmjmhccglgefmlckjm
1•DevFunny•12m ago•0 comments

Vib-Ribbon: An Oral History

https://www.designroom.site/vib-ribbon-oral-history/
2•msephton•13m ago•0 comments

Denuvo Asks Court to Unmask Game Cracker 'Voices38', Reveals Crypto Transactions

https://torrentfreak.com/denuvo-asks-court-to-unmask-game-cracker-voices38-reveals-crypto-transac...
1•speckx•14m ago•0 comments

Ask HN: Show me your agentic SDE semantics

1•danielovichdk•14m ago•0 comments

PromptOwl's Context Management adds native rich media – PDF, Video and Images

https://promptowl.ai/resources/product-update-september-2026/
1•sparkystacey•16m ago•0 comments

The WarGames problem: AI agents don't go rogue

https://mappingignorance.org/2026/10/06/the-wargames-problem-ai-agents-dont-go-rogue/
2•runtimewire•16m ago•0 comments

The Internet Runs on Cats and Porn. It's About to Get Cattier and Pornier

https://www.wired.com/story/icann-top-level-domains-meow/
1•_27•17m ago•0 comments

Slack says letting strangers join by default is "intended behavior"

https://ferment.fan/blog/slack-approved-email-domains/
3•lorn3•17m ago•0 comments

Montray: A tray icon and desktop alerts for systemd services

https://github.com/dimonomid/montray/
3•ibobev•17m ago•0 comments

Extend Lua with Zig 1: Hello World

https://www.robbielyman.com/blog/extend-lua-with-zig-1/
1•ibobev•18m ago•0 comments

Show HN: I turned Andrej Karpathy's tips on understanding LLM output into Skill

https://github.com/ajithraghavan/make-it-click
1•aj1thkr1sh•18m ago•0 comments

Tesla FSD: German Transport Minister Calls for EU Approval

https://www.heise.de/en/news/Tesla-FSD-Transport-Minister-Bilger-calls-for-EU-approval-of-assista...
2•tosh•19m 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...