Mermaid to ASCII art (mermaid-ascii)

Simon Willison · Simon Willison · 2026-07-16

Simon Willison used Claude Fable 5 to compile the AlexanderGrooff/mermaid-ascii Go library to WebAssembly, producing a browser-based Mermaid-to-ASCII art converter with color support superior to a prior Rust implementation.

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AI-Assisted Coding Culture: Landmark Rewrites, PR Description Backlash, and Prompting Debates

Extraction

Topics: webassemblydeveloper-toolsai-assisted-programminggo-languagemermaid-diagrams

Claims

The Go library mermaid-ascii is older and more feature-complete than the Rust implementation Willison previously compiled to WASM.
Claude Fable 5 was used to perform the Go-to-WebAssembly compilation.
The Go-based tool supports color output, which the earlier Rust version did not.

Key quotes

After building the Mermaid to ASCII tool based on Grok Build's Rust code I learned that there's an older, more fully-featured Go library called AlexanderGrooff/mermaid-ascii that implements a similar pattern, so I had Claude Fable 5 compile that one to WebAssembly as well so I could compare the two.