This is the repository for Lean 4, which is currently being released as milestone releases towards a first stable release. Lean 3 is still the latest stable release.

• Quickstart
• Walkthrough installation video
• Quick tour video
• Homepage
• Theorem Proving Tutorial
• Functional Programming in Lean
• Manual
• Release notes starting at v4.0.0-m3
• Examples
• FAQ

See Setting Up Lean.

Please read our Contribution Guidelines first.

See Building Lean.