flake.nix

{
  description = "A Nix-flake-based Elixir development environment";

  inputs.nixpkgs.url = "https://flakehub.com/f/NixOS/nixpkgs/0.1.*.tar.gz";

  outputs = { self, nixpkgs }:
  let
    supportedSystems = [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
    forEachSupportedSystem = f: nixpkgs.lib.genAttrs supportedSystems (system: f {
      pkgs = import nixpkgs { inherit system; overlays = [ self.overlays.default ]; };
    });
  in
  {
    overlays.default = final: prev: rec {
      # documentation
      # https://nixos.org/manual/nixpkgs/stable/#sec-beam

      # ==== ERLANG ====

        # use whatever version is currently defined in nixpkgs
        # erlang = pkgs.beam.interpreters.erlang;

        # use latest version of Erlang 27
        erlang = final.beam.interpreters.erlang_27;

        # specify exact version of Erlang OTP
        # erlang = pkgs.beam.interpreters.erlang.override {
          #   version = "26.2.2";
          #   sha256 = "sha256-7S+mC4pDcbXyhW2r5y8+VcX9JQXq5iEUJZiFmgVMPZ0=";
          # }

          # ==== BEAM packages ====

            # all BEAM packages will be compile with your preferred erlang version
            pkgs-beam = final.beam.packagesWith erlang;

            # ==== Elixir ====

              # use whatever version is currently defined in nixpkgs
              # elixir = pkgs-beam.elixir;

              # use latest version of Elixir 1.17
              elixir = pkgs-beam.elixir_1_17;

              # specify exact version of Elixir
              # elixir = pkgs-beam.elixir.override {
                #   version = "1.17.1";
                #   sha256 = "sha256-a7A+426uuo3bUjggkglY1lqHmSbZNpjPaFpQUXYtW9k=";
                # };
    };

    devShells = forEachSupportedSystem ({ pkgs }: {
      default = pkgs.mkShell {
        packages = with pkgs; [
          # use the Elixr/OTP versions defined above; will also install OTP, mix, hex, rebar3
          elixir

          # mix needs it for downloading dependencies
          git

          # probably needed for your Phoenix assets
          nodejs_20

          elixir-ls

        ]
        ++
        # Linux only
        pkgs.lib.optionals pkgs.stdenv.isLinux (with pkgs; [
          gigalixir
          inotify-tools
          libnotify
        ])
        ++
        # macOS only
        pkgs.lib.optionals pkgs.stdenv.isDarwin (with pkgs; [
          terminal-notifier
          darwin.apple_sdk.frameworks.CoreFoundation
          darwin.apple_sdk.frameworks.CoreServices
        ]);
        # shellHook = ''
        #   npm set prefix $HOME/.npm-global
        #   if [[ ":$PATH:" != *":$HOME/.npm-global/bin:"* ]]; then
        #   export PATH="$HOME/.npm-global/bin:${"$PATH:"}"
        #   fi
        #   npm install --prefix assets/
        # '';
      };
    });
  };
}