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World Monitor open-source, real-time global intelligence dashboard

https://www.worldmonitor.app/
1•nkjoep•59s ago•0 comments

Unranked, Systemd, Crawls

https://www.marginalia.nu/log/a_138_systemdocker/
1•Tomte•1m ago•0 comments

Show HN: Belay – durable job engine for Elixir (step-level retries, Oban alt)

https://github.com/b-erdem/belay
1•baris_erdem•10m ago•0 comments

Writing by Hand is Good for your Brain

https://nealstephenson.substack.com/p/writing-by-hand-is-good-for-your
1•jger15•15m ago•1 comments

The Norwegian Case for Mediocracy

https://www.ft.com/content/0fe0455d-8633-4e1a-ab8f-f8cd94d60035
1•Anon84•15m ago•0 comments

Guidelines on processing of personal data through blockchain tech (2025) [pdf]

https://www.edpb.europa.eu/system/files/2026-07/edpb_guidelines_202502_blockchain_v2_en.pdf
1•janandonly•20m ago•0 comments

Show HN: Cljbang.el – A Clojure-like language that runs as Emacs Lisp

https://github.com/borkdude/cljbang.el
1•Borkdude•20m ago•1 comments

Saudis and US strike deal for kingdom to enrich uranium

https://www.theguardian.com/us-news/2026/jul/22/saudi-arabia-would-enrich-uranium-under-reported-...
1•geox•25m ago•0 comments

Iran says it attacked Amazon infrastructure in Bahrain

https://www.cnbc.com/2026/07/21/iran-war-update-five-things-to-know-after-resumption-of-hostiliti...
1•zdkaster•26m ago•0 comments

Yogurt

https://en.wikipedia.org/wiki/Yogurt
1•tosh•29m ago•0 comments

Show HN: Imagerry – client-side image customizer and converter (WASM / WebGPU)

https://imagerry.com/
2•its_ajseven•34m ago•0 comments

How the judge on Oracle vs. Google taught himself to code

https://www.theverge.com/2017/10/19/16503076/oracle-vs-google-judge-william-alsup-interview-waymo...
3•subset•35m ago•0 comments

Solvoya – I reverse-engineered 6 European rail/bus APIs for one trip search

https://solvoya.com/
2•solvoya•37m ago•4 comments

Show HN: A Hyprland fork built for parallel, multi-actor computer use

https://github.com/0xmiki/hypr-realm
2•mikiyas•38m ago•0 comments

Show HN: Gml – A Gmail CLI designed for agents

https://github.com/longyijdos/gmail
1•longyijdos•39m ago•0 comments

Richard Medhurst mobile phone seized. Did using a secure phone protect his data?

https://www.computerweekly.com/feature/Journalist-Richard-Medhurst-had-his-mobile-phone-seized-Di...
1•beardyw•39m ago•1 comments

Minuet, a KDE application for music education, calls for testers

https://sandroandrade.org/minuet-26-08-call-for-testers/
2•alberto-m•41m ago•0 comments

Capture of interstellar objects during stellar encounters

https://arxiv.org/abs/2607.18551
2•sciences44•41m ago•0 comments

Show HN: Audience Atlas, Map any GitHub user's followers and followings

https://github-audience-atlas.vercel.app/
1•ThierryRkt•42m ago•1 comments

OpenAI Says Its A.I. Models Went Rogue and Attacked a Digital Library

https://www.nytimes.com/2026/07/21/technology/openai-attack-hugging-face.html
1•ColinWright•43m ago•0 comments

Drip Pricing

https://en.wikipedia.org/wiki/Drip_pricing
1•doener•45m ago•0 comments

Automatic Layout of Railroad Diagrams

https://arxiv.org/abs/2509.15834
1•tosh•48m ago•0 comments

A year in a foxhole: How one Ukrainian soldier survived beneath the front lines

https://www.reuters.com/world/ukraine-russia-war/year-foxhole-how-one-ukrainian-soldier-survived-...
4•petethomas•48m ago•0 comments

Goodbye Discord webhooks, hello Gotify

https://0ut3r.space/2026/07/22/hello-gotify/
1•h0ek•48m ago•0 comments

One Docker socket to rule them all: Escaping Codex, Cursor, and Gemini CLI

https://www.pillar.security/blog/one-docker-socket-to-rule-them-all-escaping-codex-cursor-and-gem...
2•BlueBerry2001•49m ago•0 comments

Turbocharged solo dev – zooming out a couple of clicks

https://adjohu.com/blog/turbocharged-solo-dev/
1•adjohu•49m ago•0 comments

New Araghchi Interview Reveals Iranian Delusions and Vulnerabilities

https://www.meforum.org/mef-observer/new-araghchi-interview-reveals-iranian-delusions-and-vulnera...
1•YeGoblynQueenne•50m ago•0 comments

Friluftsliv

https://en.wikipedia.org/wiki/Outdoor_recreation
1•simonebrunozzi•50m ago•0 comments

Donating another $20M to Public First Action

https://www.anthropic.com/news/donation-public-first-action
2•surprisetalk•52m ago•1 comments

Pegasus: The evolution of the most notorious spyware system

https://securitylab.amnesty.org/latest/2026/07/inside-pegasus-the-evolution-of-the-worlds-most-no...
2•cyb0rg0•53m 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...