We are currently updating the Lean community website to describe working with Lean 4, but most of the information you will find here today still describes Lean 3.

Pull requests updating this page for Lean 4 are very welcome. There is a link at the bottom of this page.

Please visit the leanprover zulip and ask for whatever help you need during this transitional period!

The website for Lean 3 has been archived. If you need to link to Lean 3 specific resources please link there.

CI for Lean projects on GitHub #

The Lean community offers a number of GitHub Actions scripts to help maintain Lean projects. If you include these scripts in your repository, they will help to keep your project up-to-date and warn you when it fails to build.

You can copy the text below into corresponding files in the /.github/workflows directory of your project. For more advanced options, see the README files for each action.

Build project and update lean-x.y.z branches #

This script will try to build every push made to every branch of your repository. When commits are pushed to the master branch, it will mirror them to the corresponding lean-x.y.z branch, where x.y.z is determined by the Lean version in leanpkg.toml.

You can use the build and update actions separately, but we recommend combining them as in the script below.

/.github/workflows/lean_build.yml

on:
  push:

jobs:
  update_lean_xyz_branch_and_build:
    runs-on: ubuntu-latest
    name: Update lean-x.y.z branch and build project
    steps:

    - name: checkout project
      uses: actions/checkout@v2
      with:
        fetch-depth: 0

    - name: update branch
      if: github.ref == 'refs/heads/master'
      uses: leanprover-contrib/update-versions-action@master

    - name: build project
      uses: leanprover-contrib/lean-build-action@master

Upgrade Lean and mathlib versions on schedule #

This script will try once a day to update the versions of Lean, mathlib, and any other projects that yours depends on. If it succeeds, it will push the new leanpkg.toml to your master branch. If it fails, it will open an issue on your project. (Don't worry, it won't spam you with repeated failures.)

You can change the schedule and frequency of the upgrade by modifying the cron schedule expression.

/.github/workflows/upgrade_lean.yml

on:
  schedule:
    - cron: '0 2 * * *' # once a day at 2am UTC

jobs:
  upgrade_lean:
    runs-on: ubuntu-latest
    name: Bump Lean and dependency versions
    steps:
      - name: checkout project
        uses: actions/checkout@v2
      - name: upgrade Lean and dependencies
        uses: leanprover-contrib/lean-upgrade-action@master
        with:
          repo: ${{ github.repository }}
      access-token: ${{ secrets.GITHUB_TOKEN }}
      - name: update version branches
        uses: leanprover-contrib/update-versions-action@master