Gulp - sassIn instead of stylesIn - Laravel 5.2

I know of the function mix.stylesIn('path/to/folder'), but this only compiles css and not sass. Is it possible to compile all sass files in a folder or do I have to use an array of all sass files?

Like:

 mix.sass([
    'app.scss',
    'controllers.scss'
], 'public/assets/css');

via Chebli Mohamed