let pkgs = (import <nixpkgs> {});
    haskellPackages = pkgs.recurseIntoAttrs (pkgs.haskellPackages.override {
        extension = self : super :
        let callPackage = self.callPackage;
        in {
          thisPackage = haskellPackages.callPackage (import ./default.nix) {};
        };});
in pkgs.lib.overrideDerivation haskellPackages.thisPackage (old: {
  buildInputs = old.buildInputs ++ [
    haskellPackages.cabalInstall
  ];
})