{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
    systems.url = "github:nix-systems/default";

    fenix.url = "github:nix-community/fenix";
    fenix.inputs.nixpkgs.follows = "nixpkgs";
  };

  outputs = { self, nixpkgs, systems, fenix, ... }:
    let
      eachSystem = nixpkgs.lib.genAttrs (import systems);
      fenixToolchain = "default";
    in {
      packages = eachSystem (system:
        let
          pkgs = nixpkgs.legacyPackages.${system};
          toolchain = fenix.packages.${system}.${fenixToolchain}.toolchain;
        in {
          hello = pkgs.callPackage ./package.nix {
            rustPlatform = pkgs.makeRustPlatform {
              rustc = toolchain;
              cargo = toolchain;
            };
          };
          default = self.packages.${system}.hello;
        });

      devShells = eachSystem (system:
        let pkgs = nixpkgs.legacyPackages.${system};
        in {
          default = import ./shell.nix { inherit pkgs fenix fenixToolchain; };
        });
    };
}