Lean Programming Language

Lean is an open-source programming language and proof assistant that enables correct, maintainable, and formally verified code.

• Trustworthy: Lean's minimal trusted kernel guarantees absolute correctness in mathematical proof, software and hardware verification.
• Powerful: From elementary concepts to cutting-edge research, Lean's expressive language and extensive built-in tools let users focus on the big picture rather than routine details.
• Extensible: Lean's metaprogramming capabilities enable users to extend the language with domain-specific notations and new proof automation techniques.

Lean lets you write precise, verifiable code and formal proofs. Whether you are new or experienced, now is a great time to start.