nix-los/nixos/modules/shell.nix

{ config, lib, pkgs, ... }:

{
  options.custom.shell = {
    enable = lib.mkEnableOption "Shell configuration" // { default = true; };
    defaultShell = lib.mkOption {
      type = lib.types.str;
      default = "zsh";
      description = "Default shell (dash, zsh, fish)";
    };
  };

  config = let
    cfg = config.custom.shell;
  in lib.mkIf cfg.enable {

    programs.zsh.enable = cfg.defaultShell == "zsh";
    programs.dash.enable = true;
    programs.fish.enable = cfg.defaultShell == "fish";

    # Common shell packages
    environment.systemPackages = with pkgs; [
    ];

  };
}