I keep bumping into references to "Lean", but then find there are two GitHub repositories for Lean:

Can someone explain the difference? Is one better than the other, or do they have different purposes?


1 Answer 1


https://github.com/leanprover is the official Lean organization, and contains the original works being built by Leo de Moura and his team. It also is in particular where development of Lean 4 is happening.

https://github.com/leanprover-community is run by the broader Lean community, albeit in close contact with the Lean developers (some of whom contribute to repositories in both organizations). It hosts the community website and resources, but also Mathlib, which is in some sense Lean's "killer app" -- over a million lines of mathematics built by many mathematicians and contributors, and with extremely active continued work. As of July 2023, it has been fully migrated to Lean 4.

The leanprover-community repository also hosts a community website, including instructions for getting started with Lean 4 and Mathlib.

  • 1
    $\begingroup$ Thanks! I clarified. And no worries / rush on the internet points :) $\endgroup$
    – Julian
    Feb 9, 2022 at 2:31
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    $\begingroup$ Of interest: YouTube Lean 3 tutorial videos (Play List) which include videos of installing on Mac, Windows and Ubuntu $\endgroup$
    – Guy Coder
    Apr 14, 2022 at 10:04

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