This seems like a useful feature and not difficult to implement. We can discuss here what should be supported.
Morten's reservations (in the cited article) are reasonable. I note that J has semiduals, and that it would make sense to support structural under for dyads using semiduals. Henry Rich On Sat, Oct 14, 2023, 6:10 AM LdBeth <andp...@foxmail.com> wrote: > >>>>> In <ngekbkd--...@tutamail.com> > >>>>> "'Viktor Grigorov' via Programming" <programm...@jsoftware.com> > wrote: > > > Why does > > > (|. &. ,) i.3 3 > > > result in a domain error (likewise with &.:), while > > > ($ $ (|. @ ,) ) i.3 3 > > > doesn't? > > The domain error is raised by ,^:_1 and as in J and APL > the inverse of ravel is not defined in present time. > > This is not the first time people asking about this feature > and the APL community have given this a name "structural under" > > https://www.dyalog.com/blog/2023/01/structural-vs-mathematical-under/ > > >> ... an important reason was that Roger Hui wasn’t a big fan of the > >> proposed extension known as “structural under” > > ldbeth > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
