Robert Haas <robertmhaas@gmail.com> writes:
> On Fri, Aug 12, 2016 at 9:40 AM, Greg Stark <stark@mit.edu> wrote:
>> I wonder whether it's really worth keeping postfix operators. They
>> seem to keep causing these kinds of headaches and I wonder how much
>> the grammar tables would be simplified by removing them.
> I've wondered the same thing at other times. The only postfix
> operator we ship in core is numeric_fac, and frankly it doesn't seem
> worth it just for that. If we decided that factorial(n) was adequate
> notation for that case, and that we didn't care about any hypothetical
> user-defined postfix operators either, I think we simplify or improve
> a number of things.
[ quick experiment... ] Simply removing the two postfix-operator
productions produces no meaningful savings (~0.5%), which is unsurprising
because after all they're just two more productions to Bison. It's
possible we could save more by simplifying the existing hacks elsewhere
in the grammar that were needed to work around ambiguities induced by
postfix operators. But that would take quite a bit of actual work,
and I suspect we'd end up with a similar result that the tables don't
actually get much smaller. You could argue for this on the grounds of
some reduced intellectual complexity in gram.y, and more forcefully on
the grounds of removing user surprise in cases like Jim's (especially if
you can find some other cases where it matters). But I doubt that we'd
get any kind of noticeable run-time or code-size win.
regards, tom lane
