{
  description = ''
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     ▀▀▀▀▀▀▀▀▀▀▀  ▀         ▀  ▀▀▀▀▀▀▀▀▀▀▀  ▀▀▀▀▀▀▀▀▀▀▀  ▀▀▀▀▀▀▀▀▀▀▀  ▀▀▀▀▀▀▀▀▀▀▀  ▀         ▀       ▀       ▀▀▀▀▀▀▀▀▀▀▀  ▀         ▀

    A basic Haskell flake for solving problems and sketching out concepts.
    https://tristancacqueray.github.io/blog/beautiful-haskell
  '';

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
    flake-parts.url = "github:hercules-ci/flake-parts";

    git-hooks-nix.url = "github:cachix/git-hooks.nix";
    git-hooks-nix.inputs.nixpkgs.follows = "nixpkgs";
    treefmt-nix.url = "github:numtide/treefmt-nix";
    treefmt-nix.inputs.nixpkgs.follows = "nixpkgs";
  };

  outputs = inputs @ {flake-parts, ...}:
    flake-parts.lib.mkFlake {inherit inputs;} {
      imports = [
        # To import a flake module
        # 1. Add foo to inputs
        # 2. Add foo as a parameter to the outputs function
        # 3. Add here: foo.flakeModule
        inputs.git-hooks-nix.flakeModule
        inputs.treefmt-nix.flakeModule
      ];
      systems = [
        "x86_64-linux"
        # "aarch64-linux"
        # "aarch64-darwin"
        # "x86_64-darwin"
      ];
      flake = {
        # The usual flake attributes can be defined here, including system-
        # agnostic ones like nixosModule and system-enumerating ones, although
        # those are more easily expressed in perSystem.
      };
      perSystem = {
        config,
        self',
        inputs',
        pkgs,
        system,
        ...
      }: {
        # Per-system attributes can be defined here. The self' and inputs'
        # module parameters provide easy access to attributes of the same
        # system.

        # Equivalent to  inputs'.nixpkgs.legacyPackages.hello;
        # packages.default = pkgs.hello;

        devShells.default = let
          # https://downloads.haskell.org/~ghc/9.10.3/docs/users_guide/index.html
          ghc' = pkgs.haskell.packages.ghc9103.ghcWithHoogle (
            self:
              with self; [
                relude
                split
                aeson
                random
                neat-interpolation

                # maths
                primes
                arithmoi
                parallel

                # graphing libraries!
                Chart
                Chart-cairo
              ]
          );

          clean = pkgs.writeShellScriptBin "clean" ''
            # Delete executables
              find . -type f -executable -not -path '*/.git/*' -delete

            # Delete all Haskell IR files
              find . -type f -name '*.hi' -delete
              find . -type f -name '*.o' -delete

            # Delete any test graphs created
              find . -type f -name '*.png' -delete
          '';
        in
          pkgs.mkShell {
            packages = with pkgs; [
              cowsay

              alejandra

              ghc'
              clean

              haskell-language-server
              ghcid
              hlint

              kotlin
            ];

            shellHook = ''
              ${config.pre-commit.installationScript}

              echo ".------..------..------..------..------..------..------..------..------..------."
              echo "|U.--. ||N.--. ||I.--. ||V.--. ||E.--. ||R.--. ||S.--. ||A.--. ||L.--. ||=.--. |"
              echo "| (\/) || :(): || (\/) || :(): || (\/) || :(): || :/\: || (\/) || :/\: || (\/) |"
              echo "| :\/: || ()() || :\/: || ()() || :\/: || ()() || :\/: || :\/: || (__) || :\/: |"
              echo "| '--'U|| '--'N|| '--'I|| '--'V|| '--'E|| '--'R|| '--'S|| '--'A|| '--'L|| '--'=|"
              echo "[------'[------'[------'[------'[------'[------'[------'[------'[------'[------'"
              echo ".------..------..------..------..------..------..------..------..------..------."
              echo "|C.--. ||A.--. ||L.--. ||C.--. ||U.--. ||L.--. ||A.--. ||T.--. ||O.--. ||R.--. |"
              echo "| :/\: || (\/) || :/\: || :/\: || (\/) || :/\: || (\/) || :/\: || :/\: || :(): |"
              echo "| :\/: || :\/: || (__) || :\/: || :\/: || (__) || :\/: || (__) || :\/: || ()() |"
              echo "| '--'C|| '--'A|| '--'L|| '--'C|| '--'U|| '--'L|| '--'A|| '--'T|| '--'O|| '--'R|"
              echo "[------'[------'[------'[------'[------'[------'[------'[------'[------'[------'"

              echo " _   _         _                                 _         "
              echo "| | | |       (_)                               | | ______ "
              echo "| | | | _ __   _ __   __  ___  _ __  ___   __ _ | ||______|"
              echo "| | | || '_ \ | |\ \ / / / _ \| '__|/ __| / _[ || | ______ "
              echo "| |_| || | | || | \ V / |  __/| |   \__ \| (_| || ||______|"
              echo " \___/ |_| |_||_|  \_/   \___||_|   |___/ \__,_||_|        "
              echo "                                                           "
              echo "                                                           "
              echo " _____         _               _         _                 "
              echo "/  __ \       | |             | |       | |                "
              echo "| /  \/  __ _ | |  ___  _   _ | |  __ _ | |_   ___   _ __  "
              echo "| |     / _[ || | / __|| | | || | / _[ || __| / _ \ | '__| "
              echo "| \__/\| (_| || || (__ | |_| || || (_| || |_ | (_) || |    "
              echo " \____/ \__,_||_| \___| \__,_||_| \__,_| \__| \___/ |_|    "
            '';
          };

        pre-commit = {
          settings.hooks = {
            alejandra.enable = true;
            mdformat.enable = true;
            prettier.enable = true;
            prettier.excludes = [".*\.md" "flake.lock"];
            stylish-haskell.enable = true;
          };
        };

        treefmt = {
          programs = {
            alejandra.enable = true;
            mdformat.enable = true;
            prettier.enable = true;
            prettier.excludes = ["*.md"];
            stylish-haskell.enable = true;
          };
        };
      };
    };
}