Lean 4 fork for HoTT-compatible kernel extensions (Path types, transport, HITs). Maintained against upstream leanprover/lean4.
ae1ab94992
This PR reworks the `simp` set around the `Id` monad, to not elide or unfold `pure` and `Id.run` In particular, it stops encoding the "defeq abuse" of `Id X = X` in the statements of theorems, instead using `Id.run` and `pure` to pass back and forth between these two spellings. Often when writing these with `pure`, they generalize to other lawful monads; though such changes were split off to other PRs. This fixes the problem with the current simp set where `Id.run (pure x)` is simplified to `Id.run x`, instead of the desirable `x`. This is particularly bad because the` x` is sometimes inferred with type `Id X` instead of `X`, which prevents other `simp` lemmas about `X` from firing. Making `Id` reducible instead is not an option, as then the `Monad` instances would have nothing to key on. --------- Co-authored-by: Sebastian Graf <sg@lean-fro.org> Co-authored-by: Kim Morrison <kim@tqft.net> Co-authored-by: Paul Reichert <6992158+datokrat@users.noreply.github.com> |
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