{ ... }:

self: super:

let
  dhall-source = subdir: pkg: super.haskell.lib.overrideSrc pkg {
    src = "${super.fetchFromGitHub {
      owner = "Profpatsch";
      repo = "dhall-haskell";
      # https://github.com/dhall-lang/dhall-haskell/pull/2426
      rev = "82123817316192d39f9a3e68b8ce9c9cff0a48ed";
      sha256 = "sha256-gbHoUKIdLPIttqeV471jsT8OJz6uiI6LpHOwtLbBGHY=";
    }}/${subdir}";
  };

  # binary releases of dhall tools, since the build in nixpkgs is
  # broken most of the time. The binaries are also fully static
  # builds, instead of the half-static crap that nixpkgs produces.
  easy-dhall-nix =
    import
      (builtins.fetchTarball {
        url = "https://github.com/justinwoo/easy-dhall-nix/archive/dce9acbb99776a7f1344db4751d6080380f76f57.tar.gz";
        sha256 = "0ckp6515gfvbxm08yyll87d9vg8sq2l21gwav2npzvwc3xz2lccf";
      })
      { pkgs = self; };
in
{
  # TODO: this is to fix a bug in dhall-nix
  haskellPackages = super.haskellPackages.override {
    overrides = hsSelf: hsSuper: {
      dhall = dhall-source "dhall" hsSuper.dhall;
      dhall-nix = dhall-source "dhall-nix" hsSuper.dhall-nix;
    };
  };
  # dhall = easy-dhall-nix.dhall-simple;
  # dhall-nix = easy-dhall-nix.dhall-nix-simple;
  dhall-bash = easy-dhall-nix.dhall-bash-simple;
  dhall-docs = easy-dhall-nix.dhall-docs-simple;
  dhall-json = easy-dhall-nix.dhall-json-simple;
  dhall-lsp-server = easy-dhall-nix.dhall-lsp-simple;
  # not yet in dhall-simple
  # dhall-nixpkgs = easy-dhall-nix.dhall-nixpkgs-simple;
  dhall-yaml = easy-dhall-nix.dhall-yaml-simple;
}