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What Jev Means for the Future of Evals

https://armank.com/thoughts/3
1•armank-dev•31s ago•0 comments

Hands-On with Googlebooks

https://www.tomshardware.com/laptops/hands-on-with-googlebooks-five-models-the-new-googlebook-os-...
1•Shuddown•49s ago•0 comments

North Korea Stopped Nuclear Testing in 2017, Triggered 1k Earthquakes Since

https://www.sciencealert.com/north-korea-stopped-nuclear-testing-in-2017-but-triggered-nearly-140...
1•gmays•1m ago•0 comments

The Sun Doesn't Shine on Me (2006)

https://fullhoffman.com/2006/03/20/the-sun-doesnt-shine-on-me/
1•simonebrunozzi•5m ago•0 comments

BBC removes 11 Mitchell and Webb comedy sketches from iPlayer

https://www.bbc.co.uk/news/articles/c6jdvpr30k8jo
1•benj111•6m ago•0 comments

You're a Meat Proxy

https://twitter.com/i/status/2101779116056088732
1•Michelangelo11•6m ago•0 comments

Antigravity Spaces – Switch Antigravity IDE Projects Easily

https://github.com/ApollosWave/antigravity-spaces
1•apolloswave•8m ago•0 comments

Iron willpower is an illusion – composure is the real engine of self-control

https://drdeborst.substack.com/p/iron-willpower-is-an-illusion-composure
2•dr-j•8m ago•0 comments

Show HN: Jobs at Recently Funded Startups

https://www.vcbacked.co/jobs
1•veritas9•8m ago•0 comments

Chess Design Timeline

https://chess-timeline.vercel.app/
1•msotomorras•10m ago•1 comments

Database Normalization

https://en.wikipedia.org/wiki/Database_normalization
1•gregsadetsky•12m ago•0 comments

We Asked a Urologist Whether Icing Your Testicles Boosts Testosterone

https://geiselmed.dartmouth.edu/news/2026/we-asked-a-urologist-whether-icing-your-testicles-reall...
1•harry_nutsachs•14m ago•0 comments

Guess the Country from Demographic Data

https://www.demoguessr.com/
1•BjarkeErichsen•15m ago•1 comments

Show HN: TickerWhale – nightly 0-100 scores and fair values for 1,300 stocks

https://tickerwhale.com
1•nacer222•17m ago•0 comments

Googlebook – Meet the Lineup and pre-order

https://googlebook.google/shop/
1•bretpiatt•20m ago•1 comments

Grok 4.7 Intelligence, Performance and Price Analysis

https://artificialanalysis.ai/models/grok-4-7
3•theanonymousone•20m ago•0 comments

Show HN: Agent Chaperone – Screen AI agent tool calls and results with Jev

https://github.com/agent-chaperone/agent-chaperone
2•sepehrsafari•22m ago•0 comments

Show HN: flyOS – A fruit fly connectome simulated in real time on an iPhone

https://www.becomethefly.com
2•coryetzkorn•22m ago•0 comments

Saudi Arabia's Ceer launches flagship electric vehicles

https://www.agbi.com/manufacturing/2026/09/saudi-arabias-ceer-launches-flagship-electric-vehicles/
4•abdullahalharir•24m ago•0 comments

Modulate ML Team Announces New Public Entity Transcription Benchmark

https://www.modulate.ai/blog/modulate-ml-team-announces-new-public-entity-transcription-benchmark
1•voicevector5•25m ago•0 comments

WTF Is Up with Napster's AI Pivot?

https://tedium.co/2026/09/21/napster-ai-pivot/
2•speckx•25m ago•0 comments

Alcor: Simulate cpuid and sgdt/sidt results per-process

https://github.com/er-azh/alcor
2•Tiberium•25m ago•0 comments

Google hit with €403M fine by Irish data watchdog over GDPR violations

https://www.bbc.co.uk/news/articles/ck1e52v16ngxo
2•philbo•26m ago•0 comments

Raspberry Pi founder Eben Upton: 'I'm an Omni-geek

https://www.ft.com/content/2285c111-b103-4b04-96c7-fe26a3c04c3e
1•imichael•27m ago•0 comments

Grok 4.7 is here with Electrical engineering benchmark which beats fable 5.1 max

https://twitter.com/hive_echo/status/2102072241420898708
1•echohive42•28m ago•0 comments

Delta A21N at Kahului on Sep 19th 2026, fuel fumes on board

https://avherald.com/h?article=541628f4
2•r2sk5t•31m ago•0 comments

WWLD #1: Domains and gas station hotdogs

https://chaosguru.substack.com/p/wwld-1-domains-and-gas-station-hotdogs
3•taubek•33m ago•1 comments

The agents, they just want to talk

https://snats.xyz/pages/articles/political_ecology/the_agents_they_just_want_to_talk.html
2•snats•34m ago•1 comments

Amazon Blocks Meta's Muse AI Agent from Its Retail Site

https://www.bloomberg.com/news/articles/2026-09-21/amazon-blocks-meta-s-muse-ai-agent-from-its-re...
3•k2m•34m ago•1 comments

Show HN: Foremerge – Catch Intent Conflicts Between Parallel Coding Agents

https://github.com/naw103/foremerge
10•foremerge•34m 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...