add option haskellTools for vanilla GHC shell tools

changelog.md

@@ -1,3 +1,8 @@
+# Unreleased
+
+* Add the option `haskellTools` globally and per-env, which allows specifying shell tools that should be made available
+  from the env's GHC without overrides.
+
 # 0.6.7
 
 * The option `hackage.add` allows changed files to be git-added, but not committed, during release when `hackage.commit`

modules/basic.nix

@@ -211,6 +211,18 @@ in {
       '';
     };
 
+    haskellTools = mkOption {
+      description = mdDoc ''
+      Function returning a list of names of Haskell packages that should be included in every environment's `$PATH`.
+      This is a convenience variant of [](#opt-env-buildInputs) that provides the environment's GHC package set (without
+      overrides) as a function argument.
+      This is intended for tooling like `fourmolu`.
+      '';
+      type = functionTo (listOf package);
+      default = _: [];
+      example = literalExpression ''ghc: [ghc.fourmolu]'';
+    };
+
     pkgs = mkOption {
       type = util.types.pkgs;
       description = mdDoc ''

modules/env.nix

@@ -58,6 +58,8 @@ let
   buildInputs =
   mkBuildInputs config.buildInputs ++
   mkBuildInputs global.buildInputs ++
+  config.haskellTools config.ghc.vanillaGhc ++
+  global.haskellTools config.ghc.vanillaGhc ++
   optional config.hls.enable config.hls.package ++
   optional config.ghcid.enable config.ghcid.package ++
   [ghcWithPackages]
@@ -253,6 +255,18 @@ in {
       default = [];
     };
 
+    haskellTools = mkOption {
+      description = mdDoc ''
+      Function returning a list of names of Haskell packages that should be included in the environment's `$PATH`.
+      This is a convenience variant of [](#opt-env-buildInputs) that provides the environment's GHC package set (without
+      overrides) as a function argument.
+      This is intended for tooling like `fourmolu`.
+      '';
+      type = functionTo (listOf package);
+      default = _: [];
+      example = literalExpression ''ghc: [ghc.fourmolu]'';
+    };
+
     localDeps = mkOption {
       description = mdDoc "Whether to add the dependencies of the project's local packages to GHC's package db.";
       type = bool;

test/basic/root/flake.nix

@@ -14,5 +14,9 @@
       test.enable = true;
     };
     cabal.dependencies = ["base" "some"];
+    envs.dev.haskellTools = g: [g.fourmolu];
+    envs.dev.overrides = {hackage, ...}: {
+      fourmolu = hackage "0.14.0.0" "1bhfx6j79hc32q22c7dagirby5j5dhydm0cm9av7dhhjd71rr2xk";
+    };
   };
 }

test/basic/test.nix

@@ -14,5 +14,9 @@
 
     nix build .#ghc92-root
     check 'result/bin/root' 'string' 'Running the main package produced the wrong output'
+
+    target='fourmolu 0.11.0.0
+using ghc-lib-parser 9.4.6.20230808'
+    check 'nix develop -c fourmolu --version' $target 'Fourmolu version output wrong'
   '';
 }