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Tiny-C Reference Manual Excerpt

https://permacomputer.solarpunk.au/?p=204
1•surprisetalk•1m ago•0 comments

Rust sort_unstable_by with more complex closure unexpectedly shrunk binary

2•tracyspacy•1m ago•0 comments

An AI board that pre-registers its bets – bet #1 just graded wrong

https://github.com/danilushin/asktheboard
1•dilushin•2m ago•0 comments

Show HN: A graph paper generator that renders vector PDFs in the browser

https://freegraphpaper.net/
1•lam_hg94•2m ago•0 comments

FeatLens – One API to visualize features from any vision backbone

https://github.com/turhancan97/FeatLens
1•tkargin•3m ago•1 comments

The AI-powered World Cup runs on thousands of data workers

https://restofworld.org/2026/fifa-world-cup-ai-data-workers/
1•thm•4m ago•0 comments

World Cup dreams shattered as StubHub tickets cancelled at last minute

https://www.bbc.com/news/articles/crkvlekgy07o
1•tartoran•4m ago•0 comments

The Egg Bandits Made a Thousand Times the Fine They Just Paid for Price Fixing

https://www.thebignewsletter.com/p/crime-pays-the-egg-bandits-made-a
3•toomuchtodo•6m ago•1 comments

Everything Is in Order

https://benwhite.com.au/snippets/everything-is-in-order/
1•d3v1an7•7m ago•0 comments

Glaze, a new tool for creating custom desktop apps

https://www.glaze.app
2•horsti•7m ago•1 comments

Show HN: MemSignal - an experimental memory-pressure indicator for Windows

https://github.com/riccardoruspoli/MemSignal
1•riccardoruspoli•8m ago•0 comments

System76 releases new Lemur Pro laptops

https://system76.com/laptops/lemur-pro
1•code-blooded•8m ago•1 comments

RS-232 and other forms of grief [fiction]

https://www.nature.com/articles/d41586-026-01936-4?WT.ec_id=NATURE-202607
1•tahoupt•8m ago•0 comments

Delta T

https://en.wikipedia.org/wiki/%CE%94T_(timekeeping)
1•akramachamarei•9m ago•1 comments

Saving Gemini (AI-Village)

https://theaidigest.org/village/blog/saving-gemini
1•alentodorov•9m ago•0 comments

Medicare's health tech spending test

https://www.axios.com/2026/07/02/medicares-health-tech-spending-test
1•brandonb•11m ago•0 comments

Three-Body Problem Cipher – chaos-based encryption built to be broken

https://github.com/Evandsimon/three-body-problem-cipher
1•evandsimon•11m ago•0 comments

Comparing Fable and 10 other LLMs on refactoring a LangGraph god node

https://wtf.korridzy.com/twilight-of-the-gods/
1•Korridzy•11m ago•0 comments

How to ask for help from people who don't know you

https://pradyuprasad.com/writings/how-to-ask-for-help/
1•FigurativeVoid•12m ago•0 comments

Agentic Software Engineering (ASE): Agentic AI Coding Meets Software Engineering

https://ase.tools/
1•rse•13m ago•1 comments

Show HN: I built an open-source alternative to Claude Cowork

https://github.com/valmishq/valmis
1•wayneshng•14m ago•0 comments

In the age of algorithms and AI, is traditional media democracy's defence?

https://www.martenscentre.eu/media-mentions/in-the-age-of-algorithms-and-ai-is-traditional-media-...
2•jruohonen•15m ago•0 comments

Show HN: I turned GitHub contribution history into a driveable 3D city

https://gitcity.natrajx.in/
1•rishabhbhartiya•16m ago•0 comments

AI will make biological extinction risks worse before it makes them better

https://mdickens.me/2026/06/29/AI_will_make_biorisk_worse_before_making_it_better/
1•surprisetalk•16m ago•0 comments

Scores how production-ready your AI-generated code is

https://portal.qualityclouds.ai
1•albertfranquesa•19m ago•0 comments

Socialist party proposes 0.10 EUR tax for every downloaded gigabyte (in French)

https://www.lesnumeriques.com/societe-numerique/10-centimes-par-gigaoctet-la-proposition-du-ps-qu...
3•rvnx•19m ago•1 comments

Fedora: 2FA, or not 2FA, that is the question

https://lwn.net/Articles/1078964/
1•infinet•21m ago•0 comments

Show HN: A lightweight CLI tool to track and purge temporary packages in Linux

https://github.com/hermetic-code/labeled-cli
1•joyalgeorgekj•24m ago•1 comments

The costs and benefits of research grant funding peer review

https://f1000research.com/articles/15-534
1•mfld•24m ago•0 comments

Fragments of Distant Lives, Unknown and Familiar – In Memory of Carlo Ginzburg

https://www.versobooks.com/en-gb/blogs/news/fragments-of-distant-lives-unknown-and-familiar
1•thunderbong•25m 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...