Adds Haskell generic builder argument modifier

This is a new argument to the Haskell builder's 'shellFor' which allows
the caller to adjust the 'genericBuilderArgs' after they are built.

One immediate application for this is that it allows users to disable
tests, enable benchmarks, etc. for _all_ packages in a given Haskell
package set.

This is often useful when so many of the derivations in the
package set have changed that most of the cache has been invalidated,
and there is no need for the user to run tests on their dependencies,
but they still want these dependencies available in their 'nix-shell'
environment for some package-under-development.

1 files changed, 3 insertions, 2 deletions

diff --git a/pkgs/development/haskell-modules/make-package-set.nix b/pkgs/development/haskell-modules/make-package-set.nix
index 4ae3f0b2427f4..c6b9f1021bca7 100644
--- a/pkgs/development/haskell-modules/make-package-set.nix
+++ b/pkgs/development/haskell-modules/make-package-set.nix
@@ -323,6 +323,7 @@ in package-set { inherit pkgs stdenv callPackage; } self // {
         # packages.  You should set this to true if you have benchmarks defined
         # in your local packages that you want to be able to run with cabal benchmark
         doBenchmark ? false
+      , genericBuilderArgsModifier ? (args: args)
       , ...
       } @ args:
       let
@@ -439,7 +440,7 @@ in package-set { inherit pkgs stdenv callPackage; } self // {
         # This is a derivation created with `haskellPackages.mkDerivation`.
         #
         # pkgWithCombinedDeps :: HaskellDerivation
-        pkgWithCombinedDeps = self.mkDerivation genericBuilderArgs;
+        pkgWithCombinedDeps = self.mkDerivation (genericBuilderArgsModifier genericBuilderArgs);
 
         # The derivation returned from `envFunc` for `pkgWithCombinedDeps`.
         #
@@ -453,7 +454,7 @@ in package-set { inherit pkgs stdenv callPackage; } self // {
         # pkgWithCombinedDepsDevDrv :: Derivation
         pkgWithCombinedDepsDevDrv = pkgWithCombinedDeps.envFunc { inherit withHoogle; };
 
-        mkDerivationArgs = builtins.removeAttrs args [ "packages" "withHoogle" "doBenchmark" ];
+        mkDerivationArgs = builtins.removeAttrs args [ "genericBuilderArgsModifier" "packages" "withHoogle" "doBenchmark" ];
 
       in pkgWithCombinedDepsDevDrv.overrideAttrs (old: mkDerivationArgs // {
         nativeBuildInputs = old.nativeBuildInputs ++ mkDerivationArgs.nativeBuildInputs or [];