Overhaul CI

Author: hasufell

.github/workflows/ci.yml

@@ -7,14 +7,78 @@ on:
   push:
     branches: [ "master" ]
 
+defaults:
+  run:
+    shell: bash
+
 jobs:
-  ghc:
+  tested-with-matrix:
+    name: "Generate matrix from cabal"
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.matrix }}
+    runs-on: ubuntu-latest
+    steps:
+      - name: Extract the tested GHC versions
+        id: set-matrix
+        uses: kleidukos/get-tested@v0.1.9.1
+        with:
+          cabal-file: mtl.cabal
+          ubuntu-version: "latest"
+          macos-version: "latest"
+          windows-version: "latest"
+          version: 0.1.9.1
+
+  # workaround for https://github.com/Kleidukos/get-tested/issues/93
+  tested-with-ghcs:
+    runs-on: ubuntu-latest
+    needs: ["tested-with-matrix"]
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.matrix }}
+
+    steps:
+    - name: Generate output
+      id: set-matrix
+      run: |
+        set -euo pipefail
+        ghc_versions=$(echo '${{ needs.tested-with-matrix.outputs.matrix }}' | jq -c -r '[.include[].ghc] | unique')
+        echo "${ghc_versions}"
+        echo matrix="${ghc_versions}" >> "$GITHUB_OUTPUT"
+
+  lts-matrix:
+    runs-on: ubuntu-latest
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.matrix }}
+
+    steps:
+    - name: Generate output
+      id: set-matrix
+      run: |
+        : "${STACK_TEST_NUM:=4}"
+        set -euo pipefail
+
+        # the input is something like this:
+        #   {"lts":"lts-24.36", "lts-0":"lts-0.7", "lts-1":"lts-1.15", "nightly":"nightly-2026-04-10"}
+        # and we want the last n LTS, sorted and deduplicated without nightlies:
+        #   lts-0.7 lts-1.15 lts-24.36
+        lts_versions=$(curl -s https://www.stackage.org/download/snapshots.json | jq -c -r --arg n "$STACK_TEST_NUM" '
+          [.[] | select(startswith("nightly") | not)]
+          | unique
+          | sort_by(split("-")[1] | split(".") | map(tonumber))
+          | .[-(($n | tonumber)):]
+        ')
+        echo "${lts_versions}"
+        echo matrix="${lts_versions}" >> "$GITHUB_OUTPUT"
+      env:
+        STACK_TEST_NUM: ${{ vars.STACK_TEST_NUM }}
+
+  cabal:
     name: "GHC ${{ matrix.ghc }} on ${{ matrix.os }}"
     runs-on: ${{ matrix.os }}
+    needs: ["tested-with-ghcs"]
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        ghc: ['8.10', '9.2', '9.8', '9.10', '9.12']
+        ghc: ${{ fromJSON(needs.tested-with-ghcs.outputs.matrix) }}
         exclude:
           - os: macos-latest
             ghc: '8.10'  # ghc-8.10 does not support ARM
@@ -25,26 +89,71 @@ jobs:
 
       - name: Set up Haskell
         id: setup-haskell
-        uses: haskell-actions/setup@v2
+        uses: haskell/ghcup-setup@v1
+        with:
+          ghc: ${{ matrix.ghc }}
+          cabal: 'latest'
+          stack: 'latest'
+          stack-hook: true
+
+      - name: Prepare build dir
+        run: |
+          cabal sdist -z -o .
+          cabal get mtl-*.tar.gz
+          rm -f cabal.project
+
+      - name: Build
+        run: |
+          cd mtl-*/
+          cabal build --ghc-options='-Werror' all
+
+      - uses: actions/upload-artifact@v7
         with:
-          ghc-version: ${{ matrix.ghc }}
-          cabal-version: 'latest'
+          name: ${{ matrix.os }}-${{ matrix.ghc }}-plan.json
+          path: mtl-*/dist-newstyle/cache/plan.json
 
-      - name: Configure
-        run: cabal new-configure
+#       - name: Test
+#         run: |
+#           cabal --enable-tests --test-show-details=direct all
+
+      - name: Haddock
+        run: |
+          cd mtl-*/
+          cabal haddock all
 
-      - name: Freeze
-        run: cabal freeze
+      - name: Cabal check
+        run: |
+          cd mtl-*/
+          cabal check
+
+  stack:
+    name: "LTS ${{ matrix.lts }} on ${{ matrix.os }}"
+    runs-on: ${{ matrix.os }}
+    needs: ["lts-matrix"]
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        lts: ${{ fromJSON(needs.lts-matrix.outputs.matrix) }}
+      fail-fast: false
+    steps:
+      - name: Checkout base repo
+        uses: actions/checkout@v4
 
-      - name: Cache
-        uses: actions/cache@v4
+      - name: Set up Haskell
+        id: setup-haskell
+        uses: haskell/ghcup-setup@v1
         with:
-          path: ${{ steps.setup-haskell.outputs.cabal-store }}
-          key: ${{ runner.os }}-${{ matrix.ghc }}-${{ hashFiles('cabal.project.freeze') }}
-          restore-keys: ${{ runner.os }}-${{ matrix.ghc }}-
+          stack: 'latest'
+          stack-hook: false
 
       - name: Build
-        run: cabal build
+        run: |
+          # just in case
+          rm -f stack.yaml stack.yaml.lock
+          # create stack.yaml
+          stack init --resolver=${{ matrix.lts }}
+          # build
+          stack build
 
   mhs:
     runs-on: ubuntu-latest