"Jules Alberts" <jules(dot)alberts(at)arbodienst-limburg(dot)nl> writes:
>> Note that the \df command does not show functions which return opaque.
> Thanks Peter, I didn't know that. Is there any reason why they are not
> shown?
The idea is to avoid cluttering the display with I/O functions for
datatypes, but I think it's overdoing it. Sooner or later we're going
to subdivide "opaque" into a set of more crisply-defined
pseudo-datatypes, and maybe then we can make \df smarter about what
not to show.
regards, tom lane