flake.nix

{
  description = "Machinator";

  # Nixpkgs / NixOS version to use.
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/22.11";
  };

  outputs = { self, nixpkgs }:
    let
      # System types to support.
      supportedSystems = [ "x86_64-linux" "x86_64-darwin" "aarch64-linux" "aarch64-darwin" ];

      # Helper function to generate an attrset '{ x86_64-linux = f "x86_64-linux"; ... }'.
      forAllSystems = nixpkgs.lib.genAttrs supportedSystems;

      # Nixpkgs instantiated for supported system types.
      nixpkgsFor = forAllSystems (system: import nixpkgs { inherit system; });
    in
    {
      formatter = forAllSystems (system: nixpkgsFor.${system}.nixpkgs-fmt);

      devShells = forAllSystems (system:
        let
          pkgs = nixpkgsFor.${system};
        in
        {
          default = pkgs.mkShell {
            buildInputs = with pkgs; [
              (haskell.packages.ghc810.ghcWithPackages
                     (haskellPackages: with haskellPackages; [
                       cabal-install
                     ]))
            ];
          };
        });
    };
}