Simon Willison’s Weblog

PyScript demos (via) PyScript was announced at PyCon this morning. It’s a new open source project that provides Web Components built on top of Pyodide, allowing you to use Python directly within your HTML pages in a way that is executed using a WebAssembly copy of Python running in your browser. These demos really help illustrate what it can do—it’s a fascinating new piece of the Python web ecosystem. # 30th April 2022, 9:50 pm

Testing Datasette parallel SQL queries in the nogil/python fork. As part of my ongoing research into whether Datasette can be sped up by running SQL queries in parallel I’ve been growing increasingly suspicious that the GIL is holding me back. I know the sqlite3 module releases the GIL and was hoping that would give me parallel queries, but it looks like there’s still a ton of work going on in Python GIL land creating Python objects representing the results of the query.

Sam Gross has been working on a nogil fork of Python and I decided to give it a go. It’s published as a Docker image and it turns out trying it out really did just take a few commands... and it produced the desired results, my parallel code started beating my serial code where previously the two had produced effectively the same performance numbers.

I’m pretty stunned by this. I had no idea how far along the nogil fork was. It’s amazing to see it in action. # 29th April 2022, 5:45 am

HTML event handler attributes: down the rabbit hole (via) onclick="myfunction(event)" is an idiom for passing the click event to a function - but how does it work? It turns out the answer is buried deep in the HTML spec - the browser wraps that string of code in a function(event) { ... that string ... } function and makes the event available to its local scope that way. # 26th April 2022, 8:35 pm

Mac OS 8 emulated in WebAssembly (via) Absolutely incredible project by Mihai Parparita. This is a full, working copy of Mac OS 8 (from 1997) running in your browser via WebAssembly—and it’s fully loaded with games and applications too. I played with Photoshop 3.0 and Civilization and there’s so much more on there to explore too—I finally get to try out HyperCard! # 26th April 2022, 7:16 pm

Learn Go with tests. I really like this approach to learning a new language: start by learning to write tests (which gets you through hello world, environment setup and test running right from the beginning) and use them to explore the language. I also really like how modern Go development no longer depends on the GOPATH, which I always found really confusing. # 26th April 2022, 7:12 pm

jq language description (via) I love jq but I’ve always found it difficult to remember how to use it, and the manual hasn’t helped me as much as I would hope. It turns out the jq wiki on GitHub offers an alternative, more detailed description of the language which fits the way my brain works a lot better. # 26th April 2022, 7:04 pm

A tiny CI system (via) Christian Ştefănescu shares a recipe for building a tiny self-hosted CI system using Git and Redis. A post-receive hook runs when a commit is pushed to the repo and uses redis-cli to push jobs to a list. Then a separate bash script runs a loop with a blocking “redis-cli blpop jobs” operation which waits for new jobs and then executes the CI job as a shell script. # 26th April 2022, 3:39 pm

WebAIM guide to using iOS VoiceOver to evaluate web accessibility (via) I asked for pointers on learning to use VoiceOver on my iPhone for accessibility testing today and Matt Hobbs pointed me to this tutorial from the WebAIM group at Utah State University. # 24th April 2022, 7:35 pm

Web Components as Progressive Enhancement (via) I think this is a key aspect of Web Components I had been missing: since they default to rendering their contents, you can use them as a wrapper around regular HTML elements that can then be progressively enhanced once the JavaScript has loaded. # 21st April 2022, 9:33 pm

Glue code to quickly copy data from one Postgres table to another (via) The Python script that Retool used to migrate 4TB of data between two PostgreSQL databases. I find the structure of this script really interesting—it uses Python to spin up a queue full of ID ranges to be transferred and then starts some threads, but then each thread shells out to a command that runs “psql COPY (SELECT ...) TO STDOUT” and pipes the result to “psql COPY xxx FROM STDIN”. Clearly this works really well (“saturate the database’s hardware capacity” according to a comment on HN), and neatly sidesteps any issues with Python’s GIL. # 19th April 2022, 4:57 pm

Netlify Edge Functions: A new serverless runtime powered by Deno. You can now run Deno scripts directly in Netlify’s edge CDN—bundled as part of their default pricing plan. Interesting that they decided to host it on Deno’s Deno Deploy infrastructure. The hello world example is pleasingly succinct:

export default () => new Response(“Hello world”) # 19th April 2022, 4:46 pm

How to push tagged Docker releases to Google Artifact Registry with a GitHub Action. Ben Welsh’s writeup includes detailed step-by-step instructions for getting the mysterious “Workload Identity Federation” mechanism to work with GitHub Actions and Google Cloud. I’ve been dragging my heels on figuring this out for quite a while, so it’s great to see the steps described at this level of detail. # 18th April 2022, 3:41 am

Litestream: Live Read Replication (via) The documentation for the read replication implemented in the latest Litestream beta (v0.4.0-beta.2). The design is really simple and clever: the primary runs a web server on a port, and replica instances can then be started with a configured URL pointing to the IP and port of the primary. That’s all it takes to have a SQLite database replicated to multiple hosts, each of which can then conduct read queries against their local copies. # 13th April 2022, 2:04 am

Datasette for geospatial analysis (via) I added a new page to the Datasette website describing how Datasette can be used for geospatial analysis, pulling together several of the relevant plugins and tools from the Datasette ecosystem. # 13th April 2022, 12:48 am

datasette-dashboards (via) Romain Clement’s datasette-dashboards plugin lets you configure dashboards for Datasette using YAML, combining markdown blocks, Vega graphs and single number metrics using a layout powered by CSS grids. This is a beautiful piece of software design, with a very compelling live demo. # 7th April 2022, 6:36 pm