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Planet crisis response imagery related to the earthquakes in Venezuela

https://source.coop/planet/venezuela-earthquake-2026-06-24
1•marklit•48s ago•0 comments

Swedish court says Google is to pay $1.5B to Klarna in antitrust damages

https://www.reuters.com/business/swedish-court-says-google-is-pay-15-billion-klarna-antitrust-dam...
1•giuliomagnifico•5m ago•0 comments

Emergence World: A Laboratory for Evaluating Long-Horizon Agent Autonomy

https://www.emergence.ai/blog/emergence-world-a-laboratory-for-evaluating-long-horizon-agent-auto...
1•taubek•7m ago•0 comments

Liquid Glass Component Library

https://github.com/ObaidQatan/liquid-glass-component-library
1•agilek•9m ago•0 comments

Is it practical to host a real production app on a Mac mini?

1•yesiamsumit•10m ago•0 comments

The Dogs of San Francisco

https://thedogsofsf.com/
1•bookofjoe•13m ago•0 comments

The Shifting Line Between CSS States and JavaScript Events

https://css-tricks.com/css-states-and-javascript-events/
1•redbell•14m ago•0 comments

Some Medicare beneficiaries can now get popular obesity drugs for $50 a month

https://www.npr.org/2026/05/06/nx-s1-5812662/medicare-bridge-glp1-drugs-copay
2•geox•14m ago•0 comments

The Monster and the Lamb (1978)

https://www.theatlantic.com/magazine/archive/1978/12/the-monster-and-the-lamb/662832/
1•rwmj•15m ago•1 comments

Ask HN: What will you work on when Fable 5 comes back online today?

1•kordlessagain•17m ago•0 comments

Former Microsoft engineer shrinks Notepad down to size

https://www.theregister.com/os-platforms/2026/06/30/former-microsoft-engineer-shrinks-notepad-dow...
1•theanonymousone•17m ago•0 comments

From "Surely you're joking, Mr. Feynman" (1985)

https://www.asc.ohio-state.edu/kilcup.1/262/feynman.html?repostindays=413
3•chistev•17m ago•0 comments

PearPass – Secure P2P sync and sharing of credentials, no cloud involved

https://pass.pears.com/
1•tommica•18m ago•0 comments

Show HN: Open-source library to copy-paste HTML into Figma as editable layers

https://www.figit.design/
1•mattiapomelli•20m ago•0 comments

Show HN: SlopenClaw, an AI agent that procrastinates for you

https://slopenclaw.com/
1•romainsimon•21m ago•0 comments

Show HN: Cmux-SSH-here – throwaway SSH server and deep link in one npx command

https://github.com/viktor-silakov/cmux-ssh-here
1•1105714•21m ago•0 comments

An ancient Greek computer: The Antikythera Mechanism

https://medium.com/@grbldeveloped/an-ancient-greek-computer-the-antikythera-mechanism-a838451863aa
2•GRBLDeveloped•26m ago•0 comments

How to Monitor Your Meta Tags

https://testomato.com/blog/meta-tags-monitoring/
1•dewey-decibel•29m ago•0 comments

Spain's Solar Is So Cheap Investors Are Looking for an Exit

https://www.bloomberg.com/news/newsletters/2026-06-30/spain-s-solar-is-so-cheap-investors-are-loo...
2•donohoe•30m ago•0 comments

Claude Science is Anthropic's newest flagship product

https://www.technologyreview.com/2026/06/30/1139987/claude-science-is-anthropics-newest-flagship-...
1•joozio•32m ago•1 comments

Continuous low-intensity ultrasound downregulates inflammation in macrophages

https://www.nature.com/articles/s41598-026-53228-6
1•bookofjoe•38m ago•0 comments

Why your AI bill is bigger than it should be

https://leaddev.com/ai/why-your-ai-bill-is-bigger-than-it-should-be
1•chhum•39m ago•0 comments

Opinion: I Was Not Allowed to Type Prompts into ChatGPT During My Chalk Talk

https://inpreparation.substack.com/p/opinion-i-was-not-allowed-to-type
3•mold_aid•42m ago•3 comments

Show HN: Waisly – a budgeting app that never asks for your bank login

https://getwaisly.app/en
1•Vadim7j7•42m ago•0 comments

JSP for Practical Program Design (1996)

https://archive.org/details/jspforpracticalp0000dudm
1•turtleyacht•44m ago•1 comments

Phone Number Carrier and Line Type with Python and the Telnyx Number Lookup

https://telnyx.com/resources/phone-number-carrier-lookup-python
1•harpreetseehra•46m ago•0 comments

Show HN: Irongate – Serverless Auth on AWS

https://github.com/RobinSrimal/irongate
2•maltaro•46m ago•0 comments

Show HN: HackerNows – Native iOS HN Client

https://hackernows.app/
7•maguszin•47m ago•2 comments

Private equity firm acquires MariaDB (2024)

https://k1.com/k1-acquires-mariadb/
1•elisaado•48m ago•0 comments

BIS Annual Report AI Scenarios

https://www.bis.org/publ/arpdf/ar2026e1.htm
1•2716057•50m 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...