On Wed, 20 Jun 2018, Sven Schreiber wrote:

"And slightly OT about gretl internals: Along the way I've noticed two things. The first is that the deflist() function doesn't accept a vector of series IDs as input, in the way that genr-based list construction like "list L = {1,2}" does; maybe deflist should accept that.

OK, that is now accepted in git.

The second thing is that it would be nice to have a generalization of the varnum() function, to return a vector of series IDs for a list input. See my workaround helper function listIDs in the file.

Not required. All you need do is assign the list to a matrix:
...
That's documented.