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Rails at the Center of DNSimple

https://podcast.rubyonrails.org/2462975/episodes/18999348-simone-carletti-rails-at-the-center-of-...
1•robbyrussell•27s ago•1 comments

Show HN: Greptile for Security (open source)

https://www.strix.ai/blog/pentesting-every-pull-request
1•bearsyankees•1m ago•0 comments

Domain Knowledge Is the Product

https://automato.substack.com/p/your-domain-knowledge-is-the-product
1•andrewstetsenko•2m ago•0 comments

.NET 11 Preview 3 is now available

https://devblogs.microsoft.com/dotnet/dotnet-11-preview-3/
1•vyrotek•3m ago•0 comments

Skattabugz, a fast paced shootem up for the C64, C16, Vic20, Spectrum

https://orac81.itch.io/skattabugz
1•orac81•4m ago•0 comments

Configuration flags are where software goes to rot

https://00f.net/2026/04/11/config-flags/
1•birdculture•5m ago•0 comments

Alert: GitHub Bug Exposed Webhook Secrets to Recipient Endpoints

https://exploitr.com/articles/alert-github-bug-exposed-webhook-secrets-to-recipient-endpoints/
1•ahamez•7m ago•0 comments

Has_not_been_viewed_much

https://iamwillwang.com/notes/has-not-been-viewed-much/
2•wxw•8m ago•0 comments

Physicists think they've resolved the proton size puzzle

https://arstechnica.com/science/2026/04/physicists-think-theyve-resolved-the-proton-size-puzzle/
2•A_D_E_P_T•10m ago•1 comments

Ask HN: GUI or TUI for Coding Harness?

3•nwparker•13m ago•1 comments

Free, fast diagnostic tools for DNS, email authentication, and network security

https://mrdns.com/
1•dogsnews•13m ago•0 comments

Rust should have stable tail calls

https://trifectatech.org/blog/tail-calls-project-goal/
1•fanf2•14m ago•0 comments

Show HN: ILTY – AI mental health companion that does not pat your back

1•sklyarov•15m ago•0 comments

Enterprise Cloud in Central Asia

https://hyperapp.cloud
1•akmaljonmusaev•17m ago•0 comments

Poll: How likely are you to install phone apps?

1•Bender•20m ago•3 comments

I rewrote network setup for sandboxes in Rust and it sped up by 57x

https://github.com/CelestoAI/SmolVM/pull/145
2•theaniketmaurya•21m ago•0 comments

Show HN: Run Python tools on rust agents

https://github.com/eggermarc/tools-rs
2•eggermarc•24m ago•0 comments

An exhaustive review of design tool hover areas

https://tldraw.dev/blog/a-review-of-design-tool-hover-areas
1•steveruizok•27m ago•0 comments

Show HN: Putting AI in the loop for embedded dev

https://www.electronicsconsult.com/blog/ai-assisted-hardware-in-the-loop-for-embedded-linux
1•OOHehir•27m ago•0 comments

Show HN: Pave – CLI for Managing Path

https://github.com/microsoft/pave
3•cpendery•28m ago•0 comments

NASA building the first nuclear reactor-powered spacecraft. How will it work?

https://www.technologyreview.com/2026/04/14/1135848/nasa-nuclear-powered-spacecraft/
1•gnabgib•28m ago•0 comments

A simple test-time method that beats Claude Mythos on Terminal-Bench

https://llm-as-a-verifier.notion.site
1•jackykwok•28m ago•1 comments

Synctera acquires compliance startup Cable

https://www.axios.com/pro/fintech-deals/2026/04/14/synctera-compliance-startup-cable-acquisition
1•thatdrew•28m ago•0 comments

Can Michigan Become the U.S. Drone Capital?

https://www.nytimes.com/2026/04/14/business/michigan-drone-capital.html
1•rmason•29m ago•2 comments

AgentFM – A single Go binary that turns idle GPUs into a P2P AI grid

https://github.com/Agent-FM/agentfm-core
1•s4saif•30m ago•0 comments

Demoralize Your Teams Quickly and Efficiently with Micromanagement (2010)

https://www.stellman-greene.com/2010/11/29/demoralize-your-teams-quickly-and-efficiently-with-mic...
2•downbad_•32m ago•1 comments

Whop: The Gen-Z Platform That Wants to Be Your Bank, Broker and Business

https://www.forbes.com/sites/boazsobrado/2026/04/10/one-stop-whop-the-gen-z-platform-that-wants-t...
1•rmason•33m ago•0 comments

GitHub gave webhook secrets away in webhook call

1•time4tea•33m ago•0 comments

Mississippi is running out of liquor, and it's the state's fault

https://www.washingtonpost.com/nation/2026/04/12/mississippi-liquor-sales-breakdown/
2•paulpauper•34m ago•1 comments

Mamdani Plans to Open City-Owned Grocery Store in East Harlem

https://www.nytimes.com/2026/04/12/nyregion/mamdani-city-owned-grocery-store-la-marqueta.html
5•paulpauper•35m ago•1 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•11mo ago

Comments

prezjordan•11mo 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•11mo ago
Unintentional humour with how the title got cut off?
pixelpoet•11mo ago
The title stops just short of the
johnisgood•11mo ago
"to the point", I presume, based on its README.
pjmlp•11mo ago
A side effect of the small length available for titles and the whole titles should not be editoralised point of view.
Jtsummers•11mo 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•11mo ago
It's hard to check if titles fit if you use a bot to repost from other sites.
Jtsummers•11mo 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•11mo 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•11mo 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•11mo ago
APL used ¯3 for negative 3; J went underscore to be similar but ascii.
gitroom•11mo ago
Underscore stuff always throws me off - never quite got used to how J does it. Gotta respect the weird choices though.
jbverschoor•11mo ago
Not the same as (Visual) J++. Great IDE btw
vintagedave•11mo 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•11mo 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•11mo ago
Uiua?
binary132•11mo ago
interesting, I have not seen this one
preguntador•11mo ago
12j34 is 12j + 34 or 12 + 34j?
quartern•11mo ago
12 + 34j as per https://code.jsoftware.com/wiki/Vocabulary/Constants#Complex...