"It takes far longer to tell an AI what you want than to write a regex yourself."
My experience is the exact opposite. Writing anything but the simplest regex by hand still takes me significant time, and I've been using them for decades.
Getting an LLM to spit out a regex is so much less work. Especially since an LLM already knows the details of the different potential dialects of regex.
I use them to write regexes in PostgreSQL, Python, JavaScript, ripgrep... they've turned writing a regex from something I expect to involve a bunch of documentation diving to something I'll do on a whim.
Here's a recent example - my prompt included a copy of a PostgreSQL schema and these instructions:
Write me a SQL query to extract
all of my images and their alt
tags using regular expressions.
In HTML documents it should look
for either
I ended up with 100 lines of SQL:
https://gist.github.com/simonw/5b44a662354e124e33cc1d4704cdb...The markdown portion of that is a good example of the kind of regex I don't enjoy writing by hand, due to the need to remember exactly which characters to escape and how:
(REGEXP_MATCHES(commentary,
'!\[([^\]]*)\]\(([^)]*)\)', 'g'))[2] AS src,
(REGEXP_MATCHES(commentary,
'!\[([^\]]*)\]\(([^)]*)\)', 'g'))[1] AS alt_text
Full prompt and notes here:
https://simonwillison.net/2025/Apr/28/dashboard-alt-text/