{nixpkgs ? import <nixpkgs> }:
nixpkgs {
  config = {
    allowUnfree = true;
    packageOverrides = pkgs: {
      haskellPackages = pkgs.haskellPackages.override {
        overrides = self: super: {
          sdl2 = pkgs.haskell.lib.dontCheck super.sdl2;
          sdl2-image = pkgs.haskell.lib.dontCheck super.sdl2-image;
          common = self.callPackage ./common {};
          lesson01 = self.callPackage ./examples/lesson01 {};
          lesson02 = self.callPackage ./examples/lesson02 {};
          lesson03 = self.callPackage ./examples/lesson03 {};
          lesson04 = self.callPackage ./examples/lesson04 {};
          lesson05 = self.callPackage ./examples/lesson05 {};
          lesson06 = self.callPackage ./examples/lesson06 {};
          lesson07 = self.callPackage ./examples/lesson07 {};
          lesson08 = self.callPackage ./examples/lesson08 {};
          lesson09 = self.callPackage ./examples/lesson09 {};
          lesson10 = self.callPackage ./examples/lesson10 {};
          lesson11 = self.callPackage ./examples/lesson11 {};
          lesson12 = self.callPackage ./examples/lesson12 {};
          lesson13 = self.callPackage ./examples/lesson13 {};
          lesson14 = self.callPackage ./examples/lesson14 {};
          lesson15 = self.callPackage ./examples/lesson15 {};
          lesson17 = self.callPackage ./examples/lesson17 {};
        };
      };
    };
  };
}