Simon Willison — 2026-07-17#

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Simon continues his exploration of LLM-assisted tool building by compiling an existing Go library into WebAssembly using Claude Fable 5. It’s a great example of using AI to rapidly prototype and compare different implementations of a small, sharp utility directly in the browser.

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Mermaid to ASCII art (mermaid-ascii) After recently building a Mermaid-to-ASCII tool using Grok Build’s Rust code, Simon discovered an older, more feature-rich Go library by AlexanderGrooff. To compare the two implementations, he used Claude Fable 5 to compile the Go version into WebAssembly. Notably, this newly ported tool also includes support for colors.