Welcome to “stupid jj tricks”. Today, I’ll be taking you on a tour through many different jj configurations that I have collected while scouring the internet. Some of what I’ll show is original research or construction created by me personally, but a lot of these things are sourced from blog post, gists, GitHub issues, Reddit posts, Discord messages, and more.

I started writing this post because, for whatever reason, I keep forgetting what the difference is between a ring and a group, which is funny to me because I never forget the difference between a semiring and a semigroup – although other people do, because it’s quite easy to forget! So, I wanted a fast reference to the kinds of algebraic structures that I am most often dealing with in one way or another, usually because I’m writing Haskell (which has some reliance on terminology and structure from abstract algebra and category theory) or I’m trying to read a book about category theory and they keep talking about “groups.” Wikipedia, of course, defines all these structures, and that’s fine, but what I need in those times is more of a refresher than an in-depth explanation.

This web app displays notes and slides in separate windows,
keeping both synchronised.
It accepts simple, double-width, or double-height PDF presentations:

In functional programming,
combinator libraries refer to a design style that emphasizes bottom-up program construction.
Such libraries define a few core data types
and provide constructors—functions that create initial objects—and combinators—functions that build larger objects from smaller pieces.

Combinators enable the programmer to use intuitive visual and spatial reasoning
that’s vastly more powerful than linear language processing.
As a result, solving problems with combinators feels like playing with lego pieces.

The solution to all of these problems

I humbly put forward that modern web development provides us all the utilities to move away from class names and implement something much more robust, with some fairly straightforward changes:

Attributes

Attributes allow us to parameterise a component using a key-value representation, very similar to Map<string, T>. Browsers come with a wealth of selector functions to parse the values of an attribute.

Extra is different than More. Extra is finishing those two screens, but then researching a new library for form validation that might reduce the boilerplate code. Or it's learning ways to protect against common security vulnerabilities from data entry. These little off-ramps from the main highway of Normal Work could be dead-ends and not have any practical value to the project. But they might also be important contributions. And that's the thing with Extra. While the tangible value to the project is uncertain (it could be nothing this time or it could be something), the value to you is real.

useDeferredValue is one of the most underrated React hooks. It allows us to dramatically improve the performance of our applications in certain contexts. I recently used it to solve a gnarly performance problem on this blog, and in this tutorial, I'll show you how! ⚡

Everything you need to write flexible, future-proof Rust applications using hexagonal architecture.

A somewhat compact implementation of the awk programming language

Permacomputing is both a concept and a community of practice oriented around issues of resilience and regenerativity in computer and network technology inspired by permaculture.

Official website of the Pimalaya project.

Featureful zsh prompt.

There’s plenty of information out there on how to scale Django to handle numerous requests per second, but most of it…

I've been running NetBSD on a RockPro64 since NetBSD 10-BETA, and I'm still happy with it now with NetBSD 10-RELEASE. I'm always looking for hardware to hack NetBSD though, and I recently watched a FOSDEM 2024 video: NetBSD 10: Thirty years, still going strong!. The Pinebook Pro laptop was mentioned at one point, which has the same RockChip SoC as the RockPro64. That reminded me I'd been wanting to give this inexpensive ARM 64 laptop a try.