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A "proof" of Fermat's Last Theorem that fits the margin

https://blog.trailofbits.com/2026/09/09/a-proof-of-fermats-last-theorem-that-fits-the-margin/
2•camel-cdr•1m ago•0 comments

"Just" a Library

https://emot.substack.com/p/just-a-library
1•emot•2m ago•0 comments

In an Age of AI, a Physicist Seeks What Endures

https://www.quantamagazine.org/in-an-age-of-ai-a-physicist-seeks-what-endures-20260903/
1•ibobev•5m ago•0 comments

Live from ICM 2026: What Is Math for in the Age of AI?

https://www.quantamagazine.org/live-from-icm-2026-what-is-math-for-in-the-age-of-ai-20260903/
1•ibobev•6m ago•0 comments

Building Software Is Learning

https://registerspill.thorstenball.com/p/building-software-is-learning
2•fagnerbrack•6m ago•0 comments

C++26: Module Improvements

https://www.sandordargo.com/blog/2026/09/09/cpp26-modules
1•ibobev•6m ago•0 comments

Pisa 2025 Volume 1 – Future Ready Students

https://www.oecd.org/en/publications/2026/09/pisa-2025-results-volume-i_5265bfb1.html
1•hunglee2•6m ago•0 comments

NLnet announces 60 projects stengthening the digital commons

https://nlnet.nl/news/2026/20260808-60-new-projects.html
1•maelito•8m ago•0 comments

OpenAI/Hugging Face incident – Independent investigation of agents' behavior [pdf]

https://metr.org/hugging-face-incident-report-aug-2026.pdf
1•nns•8m ago•0 comments

ALdía – Self-hosted business engine with permissioned MCP tools for agents

https://github.com/jonalemndi2/ALdia
1•jonathanalemand•9m ago•0 comments

Show HN: Revliu – Multi-touch attribution from acquisition to revenue

https://www.revliu.com/demo
1•TychiqueY•9m ago•0 comments

Show HN: Wax – A language for reproducible, changeable, replayable programs

https://waxlang.dev/doom
1•weichx•10m ago•1 comments

Don't Let Architecture Astronauts Scare You

https://www.joelonsoftware.com/2001/04/21/dont-let-architecture-astronauts-scare-you/
2•glub•10m ago•0 comments

Post-Training RLM Agents for End-to-End M&A Diligence

https://www.harvey.ai/blog/post-training-rlm-agents-for-m-and-a-diligence
1•yarapavan•10m ago•0 comments

Claude Fable 5.1 Solves the Cyphral Distich

https://www.vals.ai/blogs/fable-solves-cyphral-distich
1•simonw•10m ago•0 comments

Show HN: DortDB, a TS library for mixed-lang queries on JavaScript structures

https://github.com/filipjezek/dortdb
2•jeeza•12m ago•0 comments

Fewer and Fewer Students Earn Degrees in the Humanities

https://dailynous.com/2026/09/09/fewer-and-fewer-students-earn-degrees-in-the-humanities/
2•mdp2021•13m ago•0 comments

Draw on Mapbox, MapLibre, Google, Leaflet, or ArcGIS in React

https://github.com/orange-groove/react-map-annotate
3•agroves333•14m ago•0 comments

Show HN: Seams handles access, spend caps, and metering on one request path

https://ourseams.com/
3•kositheastro•15m ago•1 comments

Show HN: GuardRail, shell guards that stop Claude Code before it pushes to main

https://github.com/FvdHMBAI/guardrail
4•promptandbuild•16m ago•0 comments

Show HN: I rewrite my game while it is still running

https://github.com/AtomiJD/jdBasic
2•atomijd•17m ago•1 comments

Malware Analysis in the Age of AI: What Still Requires Human Skill?

https://trainsec.net/library/career-guides/malware-analysis-in-the-age-of-ai-what-still-requires-...
2•syumei•17m ago•0 comments

iTerm2 3.7.0

https://iterm2.com/downloads.html
2•ahamez•18m ago•0 comments

vLLM 0.29.0: Model Runner V2 is now the default

https://github.com/vllm-project/vllm/releases/tag/v0.29.0
2•joshcsimmons•18m ago•0 comments

Show HN: GPT 6 Astra in Lanes

https://lanes.sh/blog/whats-new-v049-astra-is-a-banger-and-codex-got-a-lot-better
4•s-xyz•19m ago•0 comments

PauseAI: Theory of Change

https://pauseai.info/theory-of-change
1•0xDEAFBEAD•20m ago•0 comments

It's Getting Harder to Return Things–and It's Making Shoppers Mad

https://www.wsj.com/business/retail/its-getting-harder-to-return-thingsand-its-making-shoppers-ma...
2•thm•21m ago•0 comments

Show HN: Starwell – give AI agents real statistics instead of made up numbers

https://starwell.dev/
1•adarsh4052•22m ago•1 comments

Show HN: URL Roulette – redesigned site for discovering human-submitted links

https://urlroulette.net/
1•mmathias•23m ago•0 comments

We're providing Muse for free for up to 100M tokens per week

https://www.threads.com/@zuck/post/DdCYWl7GktV
1•bookofjoe•23m 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...