uv is a blazing fast Python package manager that aims to displace pip. It’s a really slick tool that lets you go from git clone to executing code with all the dependencies seamlessly. All the standard accolades apply: written in Rust, beautiful terminal UI, well thought-out user ergonomics … all written by Astral, the same company that gave the Python community ruff.
But what makes it so damn fast? Under the rusty hood, the magic is even more impressive. Charlie Marsh, the project lead, presented at Jane Street and revealed some of the inner workings. The whole talk is super interesting, but some standout highlights are:
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:
- 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]'
- 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
- You can define functions that accept functions, 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]]
- You can traverse complex data structures with first-class pathing support. And you can easily modify nested structures to extend objects.
- For the category theorists/polyglots, there’s a denotational semantics paper written about
jq.
- 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.
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"
“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.