// Review guidelines for Mathlib PRs. Use when reviewing pull requests, checking code quality, or assessing whether a PR is ready to merge.
Use when asked to prove something in Lean. Covers one-step-at-a-time proving, error priority, working on the hardest case first, proof cleanup, and handling dependent type rewriting issues.
Bisect Lean toolchain versions to find where behavior changes. Use when trying to identify which Lean 4 commit caused a regression or behavior change.
Create minimal working examples (MWEs) from Lean errors for bug reports. Use when minimizing a Lean error, creating an MWE, or preparing a bug report for lean4 or mathlib4.
PR conventions for the leanprover/lean4 repository. Use when creating pull requests, writing commit messages, or following project conventions for Lean contributions.
Set up a lean4 repository clone with proper elan toolchains.
Building Mathlib
| name | mathlib-review |
| description | Review guidelines for Mathlib PRs. Use when reviewing pull requests, checking code quality, or assessing whether a PR is ready to merge. |
@[simp], @[ext], etc.).FunLike API for morphism classes, SetLike API for subobject classes.simp calls should NOT be squeezed (replaced with simp only [...]) unless there's a measured performance problem. Unsqueezed simp is more maintainable and doesn't break when lemmas are renamed.s.Nonempty over alternatives. Use hne : x ≠ ⊥ in hypotheses (easier to check), hlt : ⊥ < x in conclusions (more powerful).erw, or rfl after simp/rw usually means the API is missing lemmas.The full review guide and style references: