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Og.video – generate og:video tags that make iMessage previews fun [free/OSS]

https://og.video/
1•bookernath•7m ago•0 comments

Show HN: An open-source office suite with built-in MCP

https://github.com/freeflow-im/mcp-docs
1•scottpersinger•9m ago•0 comments

What are vector embeddings? An interactive guide

https://isaacus.com/blog/what-are-vector-embeddings
1•ubutler•14m ago•0 comments

A few seconds of loading time can push online learners off track

https://phys.org/news/2026-10-seconds-online-learners-track.html
1•santiago-pl•17m ago•0 comments

Show HN: Twigg Free and Open Source Centralized VCS

https://twigg.vc/
1•andrebianchessi•25m ago•0 comments

What Happened to the Internet? [video]

https://www.youtube.com/watch?v=E2AoYIKwJqM
1•qingcharles•28m ago•0 comments

Tesla cancels Cybertruck in Australia and NZ after 7 years of deposits

https://electrek.co/2026/10/23/tesla-cancels-cybertruck-australia-new-zealand/
3•MilnerRoute•31m ago•0 comments

CleanYourTV : Debloat Any Android or Google TV over Wi-Fi

https://github.com/Gathin23/cleanyourtv
1•saikatsg•31m ago•1 comments

Vibe coding is turning the music gear world upside down

https://www.theverge.com/gadgets/1013493/vibe-coding-ai-music-gear-hacking-custom-firmware
3•saikatsg•37m ago•0 comments

Zen Browser is the Arc replacement I was looking for

https://www.theverge.com/tech/1018275/zen-browser-arc-replacement
2•saikatsg•38m ago•1 comments

Decompressible Oracle Generators

https://gertlabs.com/blog/decompressible-oracle-generators
2•gertlabs•42m ago•0 comments

There's never any reason for a committee to set rates

https://gist.github.com/mxfactorial/d9451142ad2037d82d926e5c59d9a06d
1•mxfactorial•49m ago•0 comments

Just Dashboard open-source dashboard for managing your VPS

https://github.com/JustDashboard/Just-Dashboard
1•Wayy10•54m ago•0 comments

A New India Is Here, and It Wants to Make Things

https://www.corememory.com/p/a-new-india-is-here
1•dsr12•1h ago•0 comments

SS United States to be sunk as largest artificial reef

https://divemagazine.com/scuba-diving-news/ss-united-states-to-be-sunk-as-worlds-largest-artifici...
3•geox•1h ago•2 comments

Local-first video production workspace for people and AI agents

https://github.com/TriHerm/cutmark
3•jev-yeb•1h ago•0 comments

Failure Modes

https://www.autodidacts.io/failure-modes/
5•Curiositry•1h ago•0 comments

RSS Vault – a curated directory of RSS feeds

https://rssvault.org
2•Curiositry•1h ago•0 comments

Exploring Thurston geometries

https://www.3-dimensional.space/
1•marysminefnuf•1h ago•0 comments

Closing the Sea: Lessons from Ancient Mediterranean Blockades

https://maritime-executive.com/editorials/closing-the-sea-lessons-from-ancient-mediterranean-bloc...
2•gumby•1h ago•0 comments

An Invisible Spirit

https://animationobsessive.substack.com/p/an-invisible-spirit
3•vinhnx•1h ago•0 comments

Trace the footsteps of England's most famous accused witches

https://www.bbc.com/travel/article/20261023-the-haunting-landscapes-of-englands-accused-witches
1•1659447091•1h ago•0 comments

Can a good philsophical contribution be made just by asking a question? (2022)

https://philpapers.org/rec/HABCAG
2•schoen•1h ago•0 comments

The Tesla-SpaceX merger explained

https://finshots.in/archive/tesla-spacex-merger-explained/
2•vismit2000•1h ago•0 comments

Show HN: Proc-CLI – An agent-friendly CLI tool for process and port management

https://proc-cli.com/
3•yazeedaloyoun•1h ago•0 comments

Minecraft: Java Edition 26.3 rewritten from scratch in Rust

https://github.com/ludovic111/horizon
1•privacyishuman•1h ago•0 comments

Cognitive Mercantilism: AI panic resembles fears of early capitalism

https://contraptions.venkateshrao.com/p/cognitive-mercantilism
2•ianand•1h ago•0 comments

Show HN: How religions evolved? Charts, Maps, Citations

https://howitevolved.com/chart/
2•silly073•1h ago•0 comments

Domain UserMemory.com now available on Spaceship

https://usermemory.com
1•dev1one1•1h ago•0 comments

Sharp Tools

https://bojidar-bg.dev/blog/2025-05-28-sharp-tools/
2•Curiositry•1h 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...