You may want to write a query like KEEP(doc, @attr) so that you can define which attributes to return via a bind parameter. If you want this to be optional, then you need a ternary operator at the moment:

RETURN IS_NULL(@attr) ? doc : KEEP(doc, @attr)

KEEP() could be changed to return all attributes if the second parameter is null:

RETURN KEEP(doc, @attr) with { "attr": null }

I don't know if [null], [] or falsey values should also return doc unchanged. [] should not IMO, because it's basically an explicit list of zero attributes to keep - what is the purpose though?

Not sure if it's worth to change the behavior as there is a workaround available.

This was originally requested by user Trung in the community Slack.