{
  description = "4r";

  inputs = {
    nixpkgs.url = github:NixOS/nixpkgs/22.05;
    utils.url = github:numtide/flake-utils;

    relude-src = {
      url = github:kowainik/relude/v1.1.0.0;
      flake = false;
    };
    doctest-src = {
      url = github:sol/doctest/0.20.0;
      flake = false;
    };
    servant-src = {
      url = github:haskell-servant/servant;
      flake = false;
    };
    polysemy-zoo-src = {
      url = github:polysemy-research/polysemy-zoo/006421384e61f4a7f66670e69af926735c91a65e;
      flake = false;
    };
    polysemy-src.url = github:polysemy-research/polysemy/v1.7.1.0;
    servant-polysemy-src = {
      url = github:AJChapman/servant-polysemy/v0.1.3;
      flake = false;
    };
  };

  outputs = inputs@{ nixpkgs, utils, ... }:
    utils.lib.eachDefaultSystem (system:
      let nixpkgs' = import nixpkgs {
            inherit system;
          };
          this = ghcVersion:
            let pkgs = nixpkgs'.haskell.packages.${ghcVersion}.override {
                  overrides = (import ./nix/dependencies.nix inputs ghcVersion);
                };
             in
            pkgs.mkDerivation {
              pname = "4r";
              version = "0.1.0";
              src = ./.;
              isExecutable = true;
              executableHaskellDepends = with pkgs; [
                aeson
                ansi-terminal
                base
                commonmark
                commonmark-extensions
                cryptohash-sha512
                http-api-data
                http-client
                optparse-applicative
                polysemy
                relude
                servant
                servant-client
                servant-polysemy
                unordered-containers
              ];
              license = nixpkgs.lib.licenses.gpl3Plus;
            };
          thisNative = this "ghc922";
       in
      {
        packages.default = thisNative;

        apps.default = {
          type = "app";
          program = "${thisNative}/bin/4r";
        };

        devShells.default = thisNative.env;
      });
}