Understanding-j: An introduction to the J programming language that gets to the | Hacker News Reader

Understanding-j: An introduction to the J programming language that gets to the

github.com

62 pointstodsacerdoti19 comments

The title stops just short of the

"to the point", I presume, based on its README.

A side effect of the small length available for titles and the whole titles should not be editoralised point of view.

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.

It's hard to check if titles fit if you use a bot to repost from other sites.

Fair, they're lazy and can't be bothered to fix their bot even after 5 years of submitting messed up titles.

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.

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?

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...

APL used ¯3 for negative 3; J went underscore to be similar but ascii.

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

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.

Uiua?

interesting, I have not seen this one

12j34 is 12j + 34 or 12 + 34j?

12 + 34j as per https://code.jsoftware.com/wiki/Vocabulary/Constants#Complex...

Unintentional humour with how the title got cut off?

Not the same as (Visual) J++. Great IDE btw

Underscore stuff always throws me off - never quite got used to how J does it. Gotta respect the weird choices though.

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