Lean 4 fork for HoTT-compatible kernel extensions (Path types, transport, HITs). Maintained against upstream leanprover/lean4.
79609938a8
Before this commit, each `isDefEq u v` invocation would fail if there were pending universe level constraints. This commit, moves the postponed universe constraints back to the `MetaM` state. It also adds the combinator ```lean withoutPostponingUniverseConstraints x ``` which executes `x` and throws an error if there are pending universe constraints. We use the combinator at `elabApp` and `elabBinders`. Without this commit, we would fail to elaborate simple terms such as ```lean Functor.map Prod.fst (x s) ``` because after elaborating `Prod.fst` and trying to ensure its type match the expected one, we would be stuck at the universe constraint: ``` u =?= max u ?v ``` Another benefit of the new approach is better error messages. Instead of getting a mysterious type mismatch constraint, we get a list of universe contraints the system is stuck at. cc @Kha |
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We are currently developing Lean 4. Lean 3 is still the latest official release. This repository contains work in progress.
Important. Unless you are one of our collaborators
- We strongly suggest you use Lean 3.
- Pull requests are not welcome.
- New issues are not welcome, and will be closed without any feedback.