Leanstral: Open-source agent for trustworthy coding and formal proof engineering

Lean 4 paper (2021): https://dl.acm.org/doi/10.1007/978-3-030-79876-5_37

https://mistral.ai/news/leanstral

The real world success they report reminds me of Simon Willison’s Red Green TDD: https://simonwillison.net/guides/agentic-engineering-pattern...

> Instead of taking a stab in the dark, Leanstral rolled up its sleeves. It successfully built test code to recreate the failing environment and diagnosed the underlying issue with definitional equality. The model correctly identified that because def creates a rigid definition requiring explicit unfolding, it was actively blocking the rw tactic from seeing the underlying structure it needed to match.

Red/green TDD - Agentic Engineering Patterns

Red/green TDD - Agentic Engineering Patterns

Simon Willison’s Weblog
TDD == Prompt Engineering, for Agentic coding tasks.
Wild it’s taken people this long to realize this. Also lean tickets / tasks with all needed context to complete the task, including needed references / docs, places to look in source, acceptance criteria, other stuff.