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A single MR with 52k commits had stalled GitLab CI

https://gitlab.com/gitlab-com/gl-infra/production/-/work_items/22412
1•ramon156•38s ago•0 comments

GitLab CI Is Down

https://status.gitlab.com/
1•absqueued•1m ago•0 comments

VPSMaxxing – Migrate Your Codex, Claude Code and Other Agents to a VPS

https://github.com/Kuberwastaken/VPSmaxxing
1•kuberwastaken•2m ago•1 comments

The emergence of human influence on the ozone layer by the 1960s

https://www.pnas.org/doi/10.1073/pnas.2608286123
1•croes•3m ago•0 comments

Why does AI still forget what your codebase is "for"?

https://www.reddit.com/r/Brunelly/s/UdTgItmmlS
1•RihabAI•3m ago•0 comments

How Americans see their country's past, present and future

https://www.economist.com/graphic-detail/2026/06/29/how-americans-see-their-countrys-past-present...
1•giuliomagnifico•4m ago•0 comments

On Lazy Secrets Management

https://radekmie.dev/blog/on-lazy-secrets-management/
1•thunderbong•9m ago•0 comments

Show HN: ZenLocks – A privacy-first, subscription-free iOS screen time blocker

https://zenlocks.haogre.com
1•haogre•9m ago•0 comments

I found a vulnerability in an IRS authorized e-file vendor's app. What's next?

2•kevinminehart•11m ago•0 comments

TheoremGraph: Search 18M+ Mathematical Dependencies

https://www.theoremsearch.com/theorem-graph
1•ilreb•12m ago•0 comments

AMD Versal Architecture and Product Data Sheet (New Premium Series Gen 2)

https://docs.amd.com/v/u/en-US/ds950-versal-overview
2•oneofthose•13m ago•2 comments

Herdr: One terminal for he whole herd

https://herdr.dev/
2•rldjbpin•14m ago•0 comments

Japan has 72 micro-seasons. In 2021 it stopped officially watching most of them

https://jivx.com/microseasons
2•momentmaker•17m ago•0 comments

Hunting a 16-year-old SQLite WAL bug with TLA+

https://ubuntu.com/blog/hunting-a-16-year-old-sqlite-bug-with-tla-is-dqlite-affected
2•peterparker204•19m ago•1 comments

Tokki – language learning app because Duolingo is useless

https://apps.apple.com/us/app/tokki-chat-learn/id6768467025
1•kozielgpc•19m ago•1 comments

Claude Code Is Quietly Fingerprinting China-Linked API Routers

https://www.vincentschmalbach.com/claude-code-china-router-fingerprint/
6•vincent_s•20m ago•0 comments

6 Months of Rift

https://monster0506.dev/blog/6-months-of-rift
1•Monster0506•22m ago•0 comments

I built a browser video editor where you can verify no footage is uploaded

https://Aethercut.app
1•AetherCut•23m ago•0 comments

Should every baby's DNA be sequenced?

https://www.economist.com/science-and-technology/2026/06/29/should-every-babys-dna-be-sequenced
5•nedruod•23m ago•2 comments

Coding with DeepSeek 4 on a 128GB MacBook Pro

https://ronreiter.com/posts/running-deepseek-v4-flash-locally/
2•ronreiter•24m ago•0 comments

We built the hackathon idea we gave up on in 2011

2•EngineeringStuf•24m ago•0 comments

Building tech in the secret R&D hub

https://www.technologyreview.com/2026/06/30/1139661/building-tech-in-the-worlds-secret-rd-hub/
1•joozio•25m ago•0 comments

Sony erases digital content from libraries; reminded we don't own what we buy

https://arstechnica.com/gadgets/2026/06/sony-erases-digital-content-from-libraries-were-reminded-...
23•pseudolus•25m ago•3 comments

Digiplot – automatically extract data from chart images with AI

https://digiplot.ai/
1•Jeremy_DH•25m ago•1 comments

Microsoft builds a bouncer to keep bots out of Teams meetings

https://www.theregister.com/software/2026/06/30/microsoft-builds-a-bouncer-to-keep-bots-out-of-te...
3•LorenDB•28m ago•0 comments

All you need is PostgreSQL

https://ebellani.github.io/blog/2026/all-you-need-is-postgresql/
1•schonfinkel•28m ago•0 comments

The .join() that should be a bug

https://kronotop.com/blog/the-join-that-should-be-a-bug/
1•mastabadtomm•30m ago•0 comments

Towards Automating Scientific Review with Google's Paper Assistant Tool

https://arxiv.org/abs/2606.28277
1•Anon84•31m ago•0 comments

DoorDash robot refuses to leave SWAT operation in Arizona

https://www.the-independent.com/news/world/americas/crime/doordash-robot-swat-operation-arizona-b...
4•pseudolus•33m ago•0 comments

Identity Theft in a KIDS World

https://everettdutton.com/identity_theft_in_a_kids_world
2•edot•34m 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...