Abstract Nonsense

A place for musings, observations, design notes, quick tips...
thought gists, if you like.

11.03.2025 Inverse UMAP transforms

TIL that the dimensionality reduction algorithm UMAP¹ has support for inverse transforms!

Naturally, these are lossy inverses, but being able to generate novel examples of, for example, handwritten digits (yep, classic MNIST once again) is exceedingly cool.

The example images of handwritten digits here are sampled from the compressed planar space, and “inverted” into the original “image space”.

On a related note, the whole explanatory article for UMAP is a beautiful work of exposition, full of rich ideas that make one ponder deeply. I only wish I understood everything in here end-to-end.

11.03.2025 Irregular Expressions

Someone at work asked if it’s possible to validate credit card numbers with the Luhn algorithm in regex.

Technically, a regular language could recognise valid fixed-length credit card numbers by brute-force enumerating all possible sequences. But as a more general solution, I don’t think DFAs can support the modular arithmetic required for arbitrary sequence lengths…

Possible or not, I feel incredibly nerd sniped.

09.03.2025 Open uBanking

In Australia, we have the Consumer Data Right, a government mandated interoperability standard for the Banking (and now Energy) sector.

Also known as Open Banking, the idea is to ensure that banks expose APIs that allow safe access to your transactions history and account data without having to rely on hacky methods like screen scraping¹.

Unfortunately, due to how the standard is enforced, it’s pretty tough to get access to your own transactions without going through an “approved data broker” that charges a premium for it (like Basiq), or a free app with limited export support like Frollo.

Well, if you’re a Ubank customer, it appears some genius has reverse-engineered the internal Ubank API from examining the API requests the frontend makes, and has exposed it as a Python-consumable API with Passkey authentication support. Genius.

As an aside, the API mentions Python “descriptors”, which I’d not heard of, but seems like an intriguing functionality worth exploring…

18.02.2025 Surely you're `jq`ing

Today I read through the jq manual cover-to-cover. For those unaware, jq is a popular CLI tool to query and manipulate JSON. It’s also a Turing-complete mini-language with nice functional semantics that fits well into the ethos of composable CLI tools.

It was an exemplar of well-written technical documentation. Concise, well-written, littered with examples, and linking to an interactive playground to test-and-learn.

Some learnings:

1. It’s surprisingly functional! You can implement recursive functions and use higher-order functions! For example, here’s factorial in jq:

$ jq '[.,1]|until(.[0] < 1; [.[0] - 1, .[1] * .[0]])|.[1]'

2. It supports string interpolation - this is really nice if you’re piping stuff from JSON into a string. Coupled with format strings this becomes frictionless:

$ echo '{"search":"hello; world"}' | jq -r '@uri "https://www.google.com/search?q=\(.search)"'
# https://www.google.com/search?q=hello%3B%20world

3. You can define functions that accept functions¹, and control structures that allow labelling.

$ echo '[[1,2],[10,20]]' | jq -r 'def addvalue(f): . + [f]; map(addvalue(.[0]))'
#[[1,2,1], [10,20,10]]

4. You can traverse complex data structures with first-class pathing support. And you can easily modify nested structures to extend objects.
5. For the category theorists/polyglots, there’s a denotational semantics paper written about jq.
6. Bonus: You can build a Brainfuck interpreter in jq; and you can build a jq interpreter in jq - how’s that for bootstrapping!

Side note: This is one of my goals for 2025 - read through documentation end-to-end to develop mastery over tools. I’m trying to prioritise selectively depth over breadth.

15.02.2025 Shellshocked? Brace yourselves!

I just discovered that to capture multiple lines of stdout from a shell script and redirect them to a file, you can simply wrap them in braces!

For example, my “Create a blog post via a GitHub Action triggered on an Issue creation” workflow uses this snippet:

{
  echo "---"
  jq 'del(.content)' "parsed_issue.json" | yq -P
  echo "---"
  echo ''
  
  # Inline "content" key for the body
  jq -r '.content' "parsed_issue.json"
} > content/micro-blog/"$FILENAME"

27.01.2025 Typography in Parasite

This is awesome! Typographic Hangul from the title scene of Parasite

22.01.2025 Developer Ergonomics

“I wonder how much it is insightful to watch someone doing a workflow and to note when discomfort kicks in. That’s a really insightful thing to realize what matters from bitter experience, right? … Experience tells you when to worry about something and when not to worry about it” - Ben Sparks

That is - the rising discomfort of a programmer when employing a new tool, framework, or library is a good window into the ergonomics of how one uses your tool, framework, or library. Source: How I animate 3Blue1Brown | A Manim demo with Ben Sparks. The whole video is worth checking out! It’s a masterclass on how to construct a programatic-animation library and demonstrate how to work within it.

When I get a chance, I’d love to unpack the source code for how sprite-to-sprite transforms (part of 3B1B’s signature look) and the vectorised rendering engine are implemented with OpenGL.

18.06.2024 Audiolising SwiftUI Graphs

This demonstration of an auditory representation of a (visual) graph in Swift Charts is wild: Vectorized and function plots in Swift Charts at WWDC24.

28.05.2023 Week 22

1. I noted that there’s a difference between Anomaly detection and Outlier detection.
2. Word of the week ~ enjambement

   enjambement: (in verse) the continuation of a sentence without a pause beyond the end of a line, couplet, or stanza.

3. As an aside, I find Rust as a language fiendishly complex at a first glance, and I’m amazed by people who find it so straightforward. Having said that, I’d much rather have lived in a universe where Rust was the first ’low-level’ language I learnt instead of C.

21.05.2023 Week 21

1. Discovered the concept of similarity graphs through a talk on Uniform Manifold Approximation and Projection (UMAP) for Dimension Reduction at SciPy 2018.
2. Word of the week ~ grimoire, from French, an alteration of “grammaire” (grammar)

   grimoire: a book of magic spells and invocations.

3. Also, in the world of books: The Cossacks by Leo Tolstoy.