bspkgs: 
let
  dontCheckPackages = [ ];
  doJailbreakPackages = [ ];
  dontHaddockPackages = [ ];
  config = {
    packageOverrides = pkgs: rec {
      haskellPackages =
        let
          generatedOverrides = haskellPackagesNew: haskellPackagesOld:
            let
              toPackage = file: _: {
                name = builtins.replaceStrings [ ".nix" ] [ "" ] file;
                value = haskellPackagesNew.callPackage
                  ( ./. + "/nix/${file}") { };
              };
            in
              pkgs.lib.mapAttrs' toPackage
                (builtins.readDir ./nix);
          makeOverrides =
            function: names: haskellPackagesNew: haskellPackagesOld:
              let
                toPackage = name: {
                  inherit name;
                  value = function haskellPackagesOld.${name};
                };
              in
                builtins.listToAttrs (map toPackage names);
          composeExtensionsList =
            pkgs.lib.fold pkgs.lib.composeExtensions (_: _: {});
          manualOverrides = haskellPackagesNew: haskellPackagesOld: {
          };
        in
          pkgs.haskellPackages.override {
            overrides = composeExtensionsList [
              generatedOverrides
              (makeOverrides pkgs.haskell.lib.dontCheck dontCheckPackages)
              (makeOverrides pkgs.haskell.lib.doJailbreak doJailbreakPackages)
              (makeOverrides pkgs.haskell.lib.dontHaddock dontHaddockPackages)
              manualOverrides
            ];
          };
    };
  };
  pkgs = import bspkgs.path { inherit config; system = bspkgs.system; };
in
  pkgs.haskellPackages.cellularAutomata