Lean Theorem Prover
Lean 4 programming language and theorem prover observed · 2026-08-28
Health v2 · maintenance only
99/100
- Activity 99
- Release rhythm 98
- Longevity 100
How is this computed?
round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10) — computed 2026-09-03. Adoption (stars, forks) is never an input.
- gap_med: 27.5
- age_days: 3062
- days_rel: 12
- days_push: 7
- n_releases_24m: 31
Adoption not part of the score
8913 stars · 949 forks observed · 2026-08-28
What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-29, confidence not recorded
Lean 4 is an open-source dependently typed functional programming language and interactive theorem prover used for formalizing mathematics and writing formally verified software. It compiles ahead-of-time to native code, features a powerful metaprogramming framework, and is backed by the Lean FRO with a large mathematical library ecosystem (Mathlib).
Use cases
- formalize mathematical theorems and proofs
- write formally verified software
- learn dependent type theory and proof writing
- develop high-performance functional programs with correctness guarantees
- verify cryptographic algorithms and protocols
- AI-assisted theorem proving and autoformalization
When to choose
- you need machine-checked proofs of mathematical results
- you want formally verified code with performance competitive with C or Rust
- you need a proof assistant with strong automation and metaprogramming
- you are doing research in mathematics, logic, or verified systems
When to avoid
- you need a general-purpose language with a large ecosystem of libraries for web or app development
- your team has no background in type theory or formal methods
- you need quick scripting rather than rigorous verification
Facets
application · maturity active
programming-language compiler interpreter type-system developer-tools programming-languages mathematics education developer-tools windows cli cross-platform theorem-prover proof-assistant dependent-types formal-verification functional-programming mathlib metaprogramming interactive-proving algorithms linux macos
5 sources
- readme: https://github.com/leanprover/lean4 · fetched 2026-08-28 · 0e6af638fd5c
- homepage: https://lean-lang.org · fetched 2026-08-29 · e6d2ced4de6a
- site_page: https://lean-lang.org/install · fetched 2026-08-29 · b7373849c0c1
- site_page: https://lean-lang.org/fro/about · fetched 2026-08-29 · 8d96af3de4ec
- site_page: https://lean-lang.org/faq · fetched 2026-08-29 · c9b66bc9719c
Member repositories
| Repository | Role | Health v2 |
|---|---|---|
| leanprover/lean4 | main | 99 |
| leanprover/lean3 | mirror | 10 |
For agents
markdown · JSON · MCP: product_card(name="leanprover/lean4")
Data as of 2026-08-30T08:39:29.467469+00:00 · Report a problem