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Lean 4 fork for HoTT-compatible kernel extensions (Path types, transport, HITs). Maintained against upstream leanprover/lean4.
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Scott Morrison 5f5d579986
chore: remove unused MonadBacktrack instance for SimpM (#2943) 
We noticed at
https://github.com/leanprover/lean4/pull/2923#discussion_r1400468371
that this instance is not used. It's arguably also incorrect (as it
doesn't backtrack the `usedTheorems` field).

Seems better to just remove to avoid confusion.

Evidence that this is dead code:
* After deleting the instance, calling `saveState` in the `SimpM` monad
raises an error `failed to synthesize instance MonadBacktrack PUnit
SimpM`.
* Understanding the `MonadBacktrack` monad leads one to believe that
would have happened, via the fact that the only instances for
`MonadBacktrack` are either concrete instances (e.g. for `MetaM`,
`TacticM`, etc), or a single lifting instance `instance [MonadBacktrack
s m] [Monad m] : MonadBacktrack s (ExceptT ε m)`. (This is good and
correct behaviour: lifting instances for `MonadBacktrack` would be hard
to model.)
* Mathlib builds after the instance is removed.

Potential evidence that I have not sought, because we don't have
sufficient tooling:
* Compiling Lean/Std/Mathlib with a debugger, breaking on entering this
code.
2023-11-24 08:44:38 +00:00
.github chore: Run CI on all PRs, even base ≠ master (#2955) 2023-11-23 21:50:30 +00:00
.vscode doc: fix some syntax and link in the docs, and more 2021-10-10 11:36:43 +02:00
doc doc: Adjust contributor's docs to squash merging (#2927) 2023-11-21 10:13:43 +00:00
images
nix fix: If src is a dir, assume the lean file has the full path (#2465) 2023-08-28 14:45:45 +02:00
script chore: script/most-recent-nightly-tag uses https rather than ssh repo URL (#2951) 2023-11-23 10:27:46 +00:00
src chore: remove unused MonadBacktrack instance for SimpM (#2943) 2023-11-24 08:44:38 +00:00
stage0 chore: update stage0 2023-11-21 18:59:22 +01:00
tests fix: PackMutual: Eta-Expand as needed (#2902) 2023-11-22 14:25:56 +00:00
.gitattributes chore: Do not hide stage0/src/stdlib_flags.h from diffs 2023-09-13 19:29:25 +02:00
.gitignore chore: update tests to account for .lake 2023-11-13 20:31:24 -05:00
.ignore chore: ignore stage0/ (for rg etc.) 2022-03-18 15:28:20 +01:00
CMakeLists.txt feat: Web Assembly Build (#2599) 2023-10-04 09:04:20 +02:00
CODEOWNERS chore: more code owners 2023-11-20 09:30:18 +01:00
CONTRIBUTING.md doc: Adjust contributor's docs to squash merging (#2927) 2023-11-21 10:13:43 +00:00
default.nix doc: setup 2021-01-03 13:21:58 +01:00
flake.lock chore: Nix bump to LLVM 15 2023-07-28 10:56:54 +02:00
flake.nix chore: Nix: use strings instead of URL literals (#2172) 2023-03-28 10:10:24 +02:00
LICENSE chore: remove LICENSE header that confused GitHub 2021-11-18 09:42:35 +01:00
LICENSES chore: add GMP license for now 2021-11-18 09:42:35 +01:00
README.md doc: Update contribution guides (#2624) 2023-10-25 13:05:55 +11:00
RELEASES.md doc: release notes for recent lake fixes 2023-11-20 15:51:31 +00:00
shell.nix chore: Nix bump to LLVM 15 2023-07-28 10:56:54 +02:00

README.md

This is the repository for Lean 4.

We provide nightly releases and have just begun regular stable point releases.

About

Installation

See Setting Up Lean.

Contributing

Please read our Contribution Guidelines first.

Building from Source

See Building Lean.