Nix - selectively profiling libraries

config.nix

{ pkgs }: {
  allowUnfree = true;

  packageOverrides = super: let self = super.pkgs; in {

    haskellPackages = super.haskellPackages.override {
      overrides = self: super: {
        mkDerivation = drv: super.mkDerivation (drv // {enableLibraryProfiling = true;});
        ghc-mod  = self.callPackage /home/meditans/code/haskell/ghc-mod/default.nix {};
        cabal-helper  = self.callPackage /home/meditans/code/haskell/cabal-helper-0.3.4.0/default.nix {};
      };
    };

    haskellEnv = self.haskellPackages.ghcWithPackages
      (haskellPackages: with haskellPackages; [
        cabal2nix
        cabal-install
        stylish-haskell
        ghc-mod
        hindent
        structured-haskell-mode
        present
    ]);
  };
}