{ lib }: { assertPlatform = module: pkgs: platforms: { assertion = lib.elem pkgs.stdenv.hostPlatform.system platforms; message = let platformsStr = lib.concatStringsSep "\n" (map (p: " - ${p}") (lib.sort (a: b: a < b) platforms)); in '' The module ${module} does not support your platform. It only supports ${platformsStr}''; }; }