[Gretl-devel] Re: weird function arg bug

Am 24.10.2021 um 21:40 schrieb Allin Cottrell: > On Sun, 24 Oct 2021, Sven Schreiber wrote: >> heylist(diff(LRM))            # works! >> list oi = heylist(diff(LRM))    # fails >> </hansl> > > Specifically, the second case fails with the error message: > > "heylist: argument 1 is of the wrong type (is list, should be series)" > > In the second case gretl notices that the statement as a whole involves > assignment to a list object. Trying to be helpful, it therefore "casts" > the argument to diff(), namely LRM, to a single-member list. This > _would_ in fact be helpful if the statement were of the simpler form > > list oi = diff(LRM) # call it case B > > Why? Because diff(LRM), without a cast to list for the argument, > produces an anonymous series, and only named series (members of the > dataset) can be put into lists. Hm, thanks for the explanation... > Clearly, gretl is not clever enough here: in the heylist() context > "diff(LRM)" _should_ produce an anonymous series result; this expression > is supposed to create an argument to a function that wants a series. > Gretl doesn't understand that, unlike case B, "diff(LRM)" occurs in an > "opaque" context as an argument to heylist(). Let me just note that it wouldn't be such a big problem if in this case diff(LRM) did produce a hardwired-prefix-named internal new series d_LRM, I think, in analogy to what diff() does to list members. I'm just saying it doesn't have to be anonymous, FWIW.