nix(hlint): add option to apply inplace hlint suggestions

`postgrest-lint` now supports an optional argument `--apply-hlint-suggestions`
which applies Hlint suggestions inplace to the input haskell file.

Hlint supports this via another package `apply-refact` which is marked
broken in nixpkgs because it doesn't build with GHC 9.10, so we are using
the GHC 9.12 pinned version.

Signed-off-by: Taimoor Zaeem <taimoorzaeem@gmail.com>

Author: taimoorzaeem

default.nix

@@ -126,6 +126,11 @@ rec {
       inherit (pkgs.haskell.packages."${compiler}") ghcWithPackages;
     };
 
+  # The "apply-refact" package is marked broken in nixpkgs because it
+  # doesn't build with GHC 9.10, so we are using the GHC 9.12 pinned version.
+  # https://github.com/mpickering/apply-refact#ghc-version-compatibility
+  apply-refact = pkgs.haskell.packages.ghc912.apply-refact;
+
   # Used by CI on MacOS
   inherit (pkgs) nix-build-uncached;
 
@@ -163,7 +168,9 @@ rec {
 
   # Linting and styling tools.
   style =
-    pkgs.callPackage nix/tools/style.nix { inherit hsie; };
+    pkgs.callPackage nix/tools/style.nix {
+      inherit hsie apply-refact;
+    };
 
   # Scripts for running tests.
   tests =

nix/tools/style.nix

@@ -1,4 +1,5 @@
 { actionlint
+, apply-refact
 , black
 , buildToolbox
 , checkedShellScript
@@ -71,29 +72,42 @@ let
       {
         name = "postgrest-lint";
         docs = "Lint all Haskell files, bash scripts and github workflows.";
+        args = [
+          "ARG_OPTIONAL_SINGLE([apply-hlint-suggestions], [], [Filename to apply hlint suggestions on], [])"
+        ];
         workingDir = "/";
       }
       ''
-        echo "Linting workflows..."
-        ${actionlint}/bin/actionlint
+        if [ -z "$_arg_apply_hlint_suggestions" ]; then
 
-        echo "Scanning nix files for unused code..."
-        ${deadnix}/bin/deadnix -f
+          echo "Linting workflows..."
+          ${actionlint}/bin/actionlint
 
-        # ruff has gaps in scanning for unused code, so we use vulture
-        echo "Scanning python files for unused code..."
-        ${fd}/bin/fd '\.l?py$' \
-          | xargs ${python3Packages.vulture}/bin/vulture --exclude docs/conf.py --min-confidence 80
+          echo "Scanning nix files for unused code..."
+          ${deadnix}/bin/deadnix -f
 
-        echo "Linting python files..."
-        ${ruff}/bin/ruff check .
+          # ruff has gaps in scanning for unused code, so we use vulture
+          echo "Scanning python files for unused code..."
+          ${fd}/bin/fd '\.l?py$' \
+            | xargs ${python3Packages.vulture}/bin/vulture --exclude docs/conf.py --min-confidence 80
 
-        echo "Checking consistency of import aliases in Haskell code..."
-        ${hsie} check-aliases src/library src/executable
+          echo "Linting python files..."
+          ${ruff}/bin/ruff check .
 
-        echo "Linting Haskell files..."
-        ${fd}/bin/fd '\.l?hs$' \
-          | xargs ${hlint}/bin/hlint --hint=${hlintConfig}
+          echo "Checking consistency of import aliases in Haskell code..."
+          ${hsie} check-aliases src/library src/executable
+
+          echo "Linting Haskell files..."
+          ${fd}/bin/fd '\.l?hs$' \
+           | xargs ${hlint}/bin/hlint --hint=${hlintConfig}
+
+        else
+
+          echo "Applying Hlint suggestions..."
+          export PATH="${apply-refact}/bin:$PATH"
+          ${hlint}/bin/hlint --hint=${hlintConfig} --refactor --refactor-options="--inplace" "$_arg_apply_hlint_suggestions"
+
+        fi
       '';
 
 in