descriptive claim
Lean is both a programming language and a proof assistant, and its implementation is written in Lean.
Unresolved speaker · Mathematics Just Changed Forever — Kevin Hartnett · 26 Oct 2026
In their words
The transcript segments this claim was taken from
“Oh, Lean is both a programming language and a proof assistant. You can write codes. Lean is actually implemented in Lean itself. Uh, uh, but the cool thing is that you can prove properties about your codes.”12:58Report a misattribution
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