{
  description = "A very basic flake";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
    flake-utils.url = "github:numtide/flake-utils";
    # Add support for ocaml package overlay
    ocaml-overlay.url = "github:nix-ocaml/nix-overlays";
    ocaml-overlay.inputs.nixpkgs.follows = "nixpkgs";
  };

  outputs = { self, flake-utils, nixpkgs, ocaml-overlay }:
    flake-utils.lib.eachDefaultSystem (system: let
      pkgs = import nixpkgs {
        inherit system;
        overlays = [
          ocaml-overlay.overlays.default
        ];
      };
      # set ocaml packages' version
      ocamlPackages = pkgs.ocaml-ng.ocamlPackages_5_2;
    in {
      devShell = 
      #let
        #
      #in
        pkgs.mkShell {
          buildInputs = with pkgs; [
            ocaml
            ocamlPackages.ocaml-lsp
            ocamlPackages.findlib
            ocamlPackages.ocamlformat
            ocamlPackages.ocamlformat-rpc-lib
            ocamlPackages.utop
            dune_3
            # Project deps
            ocamlPackages.eio_main
            ocamlPackages.caqti-eio
            ocamlPackages.caqti-driver-sqlite3
            ocamlPackages.ocaml_sqlite3
            ocamlPackages.dream
            ocamlPackages.cohttp-eio
            ocamlPackages.tyxml
            ocamlPackages.tyxml-ppx
            ocamlPackages.ppx_deriving
            ocamlPackages.ppx_deriving_yojson
            ocamlPackages.ppx_assert
            ocamlPackages.ppx_inline_test
          ];
        };
    });
}