Update HLS version and add GitHub action

.github/workflows/check-formatting.yml

@@ -24,7 +24,7 @@ jobs:
 
     env:
       FOURMOLU_VERSION: "0.16.2.0"
-      STYLISH_HASKELL_VERSION: "0.14.5.0"
+      STYLISH_HASKELL_VERSION: "0.14.6.0"
 
     steps:
     - name: Download Fourmolu

.github/workflows/hls.yml

@@ -0,0 +1,53 @@
+name: "Haskell Language Server works"
+on:
+  merge_group:
+  pull_request:
+  push:
+    branches:
+      - main
+
+permissions:
+  contents: read
+
+jobs:
+
+  test-hls-works:
+    env:
+      # Modify this value to "invalidate" the cache.
+      HLS_CACHE_VERSION: "2024-07-24"
+
+
+    runs-on: ubuntu-latest
+    timeout-minutes: 60
+    steps:
+      - name: Check out repo
+        uses: actions/checkout@v4
+      - name: Install Nix with good defaults
+        uses: input-output-hk/install-nix-action@v20
+        with:
+          extra_nix_config: |
+            trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=
+            substituters = https://cache.iog.io/ https://cache.nixos.org/
+          nix_path: nixpkgs=channel:nixos-unstable 
+      - name: Open nix environment
+        uses: rrbutani/use-nix-shell-action@v1
+      - name: Update dependencies
+        run: cabal update; cabal freeze
+      - name: Obtain GHC version
+        run: |
+          echo "VERSION=$(ghc --numeric-version)" >> "$GITHUB_OUTPUT"
+        id: ghc
+      - name: HLS caching
+        uses: actions/cache@v4
+        with:
+          path: |
+            /home/runner/.cache/hie-bios
+            /home/runner/.cache/ghcide
+            /home/runner/.local/state/cabal
+            .ghc.environment.x86_64-linux-9.8.2
+            dist-newstyle
+          key: hls-cache-${{ env.HLS_CACHE_VERSION }}-${{ runner.os }}-${{ steps.ghc.outputs.VERSION }}-${{ hashFiles('**/cabal.project.freeze') }}-${{ hashFiles('**/*.cabal', '**/cabal.project') }}
+          restore-keys: |
+            hls-cache-${{ env.HLS_CACHE_VERSION }}-${{ runner.os }}-${{ steps.ghc.outputs.VERSION }}-${{ hashFiles('**/cabal.project.freeze') }}-
+      - name: Test HLS works
+        run: haskell-language-server

flake.nix

@@ -27,8 +27,9 @@
     ];
 
     # see flake `variants` below for alternative compilers
-    defaultCompiler = "ghc965";
+    defaultCompiler = "ghc982";
     haddockShellCompiler = defaultCompiler;
+    mingwVersion = "ghc965";
 
     cabalHeadOverlay = final: prev: {
       cabal-head =
@@ -82,7 +83,7 @@
 
           # we also want cross compilation to windows on linux (and only with default compiler).
           crossPlatforms = p:
-            lib.optional (system == "x86_64-linux" && config.compiler-nix-name == defaultCompiler)
+            lib.optional (system == "x86_64-linux" && config.compiler-nix-name == mingwVersion)
             p.mingwW64;
 
           # CHaP input map, so we can find CHaP packages (needs to be more
@@ -111,9 +112,9 @@
               # tools that work or should be used only with default compiler
               cabal-gild = "1.3.1.2";
               fourmolu = "0.16.2.0";
-              haskell-language-server.src = nixpkgs.haskell-nix.sources."hls-2.6";
-              hlint = "3.6.1";
-              stylish-haskell = "0.14.5.0";
+              haskell-language-server.src = nixpkgs.haskell-nix.sources."hls-2.8";
+              hlint = "3.8";
+              stylish-haskell = "0.14.6.0";
             };
           # and from nixpkgs or other inputs
           shell.nativeBuildInputs = with nixpkgs; [gh jq yq-go actionlint shellcheck cabal-head];
@@ -151,7 +152,7 @@
         flake = cabalProject.flake (
           lib.optionalAttrs (system == "x86_64-linux") {
             # on linux, build/test other supported compilers
-            variants = lib.genAttrs ["ghc8107"] (compiler-nix-name: {
+            variants = lib.genAttrs ["ghc8107" mingwVersion] (compiler-nix-name: {
               inherit compiler-nix-name;
             });
           }