Lean 4 downstream monorepo

A "downstream" monorepo of lake packages from GitHub, managed using downstream. They all use the same toolchain, and their dependencies point to each other instead of the original repos.

It is recommended to set the following environment variables while working in this repository to benefit from cross-project caching:

• LAKE_ARTIFACT_CACHE=1 to enable global lake artifact caching.
• LAKE_RESTORE_ARTIFACTS=1 to force lake to populate the .lake directories with artifacts from the global cache. Some repositories don't support the global artifact cache yet and may fail to build, test, or lint without this.

Branches

Inside this repository, the following branches exist:

• master: Follows lean4 nightly releases. Both the toolchain and the subrepos are kept up-to-date by CI.
• nightly-YYYY-MM-DD: For every nightly release, a branch of this form points to the latest commit with green CI on master using this release.
• nightly-latest: Points to the latest commit with green CI on master.

In the Lean 4 repository, the following branch exists:

• downstream: Points to the latest commit tagged with nightly-YYYY-MM-DD for which this repository has a commit with green CI.