Nix MacOS configuration

nix/darwin-configuration.nix

@@ -0,0 +1,65 @@
+{ config, pkgs, ... }: let 
+  # Mach-nix is a toolkit for constructing custom Python environments
+  mach-nix = import (builtins.fetchGit {
+    url = "https://github.com/DavHau/mach-nix/";
+    ref = "refs/tags/3.3.0";
+  }) {
+    pkgs = pkgs;
+  };
+
+  xonsh_pyenv = mach-nix.mkPython {
+    requirements = ''
+    xontrib-fzf-widgets
+    xonsh-direnv
+    '';
+  };
+
+  xonsh_with_plugins = pkgs.xonsh.overrideAttrs (old: {
+    propagatedBuildInputs = old.propagatedBuildInputs ++ xonsh_pyenv.python.pkgs.selectPkgs xonsh_pyenv.python.pkgs;
+  });
+in
+{
+
+  # List packages installed in system profile. To search by name, run:
+  # $ nix-env -qaP | grep wget
+  environment.systemPackages = with pkgs;
+    [
+    xonsh_with_plugins
+    zoxide
+    fd
+    fzf
+    ncdu
+    ripgrep
+    kitty
+    git
+    lorri
+    direnv
+    ];
+
+  # Lorri user agent
+  # from https://github.com/target/lorri/issues/96#issuecomment-579931485
+  launchd.user.agents = {
+      "lorri" = {
+      serviceConfig = {
+          WorkingDirectory = (builtins.getEnv "HOME");
+          EnvironmentVariables = { };
+          KeepAlive = true;
+          RunAtLoad = true;
+          StandardOutPath = "/var/tmp/lorri.log";
+          StandardErrorPath = "/var/tmp/lorri.log";
+      };
+      script = ''
+          source ${config.system.build.setEnvironment}
+          exec ${pkgs.lorri}/bin/lorri daemon
+      '';
+      };
+  };
+
+  # Auto upgrade nix package and the daemon service.
+  services.nix-daemon.enable = true;
+  nix.package = pkgs.nix;
+
+  # Used for backwards compatibility, please read the changelog before changing.
+  # $ darwin-rebuild changelog
+  system.stateVersion = 4;
+}