Simon Willison’s Weblog

How Regexes Work (via) They’re just simplified syntax for constructing a state machine

Posted 25th November 2003 at 12:27 am

Recent articles

The Summer of Johann: prompt injections as far as the eye can see - 15th August 2025
Open weight LLMs exhibit inconsistent performance across providers - 15th August 2025
LLM 0.27, the annotated release notes: GPT-5 and improved tool calling - 11th August 2025

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