Simon Willison’s Weblog

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Saturday, 10th January 2026

A Software Library with No Code. Provocative experiment from Drew Breunig, who designed a new library for time formatting ("3 hours ago" kind of thing) called "whenwords" that has no code at all, just a carefully written specification, an AGENTS.md and a collection of conformance tests in a YAML file.

Pass that to your coding agent of choice, tell it what language you need and it will write it for you on demand!

This meshes nearly with my recent interest in conformance suites. If you publish good enough language-independent tests it's pretty astonishing how far today's coding agents can take you!

# 11:41 pm / testing, ai, generative-ai, llms, ai-assisted-programming, drew-breunig, coding-agents

2026 » January

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