{ config, pkgs, ... }: with pkgs.lib; { ###### interface options = { hardware.sane.enable = mkOption { default = false; description = "Enable support for SANE scanners."; }; hardware.sane.snapshot = mkOption { default = false; description = "Use a development snapshot of SANE scanner drivers."; }; }; ###### implementation config = let pkg = if config.hardware.sane.snapshot then pkgs.saneBackendsSnapshot else pkgs.saneBackends; in mkIf config.hardware.sane.enable { environment.systemPackages = [ pkg ]; services.udev.packages = [ pkg ]; }; }