(Moving this to the devel list, I think it's more appropriate) On Sat, 25 May 2019, Artur Tarassow wrote: In fact we could enhance the above in 2 ways: 1) we could provide the "!" operator for lists, so that list drop = !keep would achieve the same as the command Artur used, and 2) we could enable on-the-fly computed lists in commands such as "delete", so one could conceivably use something like delete !(LRM IBO) of course step 2 would not be very easy to implement, so the question is: would it be worthwhile? ------------------------------------------------------- Riccardo (Jack) Lucchetti Dipartimento di Scienze Economiche e Sociali (DiSES) Università Politecnica delle Marche (formerly known as Università di Ancona) r.lucchetti(a)univpm.it http://www2.econ.univpm.it/servizi/hpp/lucchetti -------------------------------------------------------