{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
  };

  outputs = { self, nixpkgs, ... }@inputs:
    let
      supportedSystems = [
        "aarch64-darwin" "aarch64-linux"
        "x86_64-darwin" "x86_64-linux"
      ];

      each-system = f: nixpkgs.lib.genAttrs supportedSystems (system: f rec {
	pkgs = import nixpkgs {
	  inherit system;
	};
	inherit (pkgs) lib;
        inherit system;
      });
    in {
      # Exposed as a REPL convenience.
      _pkgs = each-system ({ pkgs, ... }: pkgs);

      packages = each-system ({ pkgs, ... }: {
        default = pkgs.callPackage ./default.nix {};
      });

      devShells = each-system ({ pkgs, system, ... }: {
	default = pkgs.mkShell {
          inputsFrom = [
            self.packages.${system}.default
          ];
	  packages = with pkgs; [
            gcc
            clang-analyzer
            clang-tools
	  ];
          # shellHook = ''
          #   [[ ! -z "$LD_LIBRARY_PATH" ]] \
          #     && export LD_LIBRARY_PATH=:$LD_LIBRARY_PATH
          #   export LD_LIBRARY_PATH="${self.packages.${system}.default.libllvm.lib}/lib$LD_LIBRARY_PATH"
          # '';
	};
      });
    };
}