Re: Interesting article on ARG work

["Dan'l Miller" <optikos@verizon.net>]

On Sunday, April 8, 2018 at 3:09:55 PM UTC-5, Dmitry A. Kazakov wrote:
> On 2018-04-08 21:48, Dan'l Miller wrote:
> > On Sunday, April 8, 2018 at 2:46:15 AM UTC-5, Dmitry A. Kazakov wrote:
> >>      if Foo then
> >> @     Bar;
> >> @  end if;
> >> @  if Boo then
> >>         Baz;
> >>      end if;
> >>
> >> would not be legal either.
> > 
> > Where ␠ is the ASCII/ISO646 space character (presented as a graphical character for visualization herein),
> > 
> >      if Foo then
> > ␠     Bar;
> > ␠  end if;
> > ␠  if Boo then
> >         Baz;
> >      end if;
> > 
> > and
> > 
> >      if Foo then
> > --     Bar;
> > --  end if;
> > --  if Boo then
> >         Baz;
> >      end if;
> > 
> > both are legal Ada statements, spurious and non sequitur evocations of the ARM notwithstanding.
> > 
> > In general, Dmitry, you seem to not understand that a generalized left-right (GLR) parser would parse both sides of the @ concurrently.  Your entire premise is that it is impossible to parse both presence and absence of @ at the same time.  In GLR, you are incorrect.
> 
> No, I don't understand what are you trying to say or how is it related 
> to the issue discussed.

I am saying that your insistence on conformance of the extent of the @-code to any portion of the BNF (or anything else) in the ARM is 100% misguided, tantamount to being a troller fisherman.

I am saying that you are 100% incorrect that only the presence or only the absence of the @-code will be compiled in the most-exemplary implementation, leaving the other uncompiled variant to bit-rot uncompiled for extended periods of time.  I am saying that you sure appear to be quite ignorant of GLR parsers' ability to parse both the presence and absence of the @-code ••concurrently in the same invocation•• of the compiler in O(n) time in this case (because the @ mechanism does not suffer combinatorial explosion of, say, C preprocessor's arbitrarily-nested #if...#endif constructs, which in their worst case can evoke GLR parsers' O(n³)-growth time on top of the combinatorial explosion's growth rate).  GLR parsers accomplish this by forking/bifurcating the push-down automata's reduced-production stack before rejoining the forks into traditional LR mode:  one fork of the bifurcated reduced-production stack for •presence• of the @-code and one fork of the bifurcated reduced-production stack for the •absence• of the @-code.  I am saying that you apparently have not even read the Wikipedia article on GLR parsers:  https://en.wikipedia.org/wiki/GLR_parser

I am saying that nearly everything that you have said among your multiple replies to Randy's @-code is hogwash and horse-hooey.  Perhaps.  Every.  Word.  Of.  It.  (especially regarding your pontifications in the large for all possible implementations that no well-oiled-machine spectacular implementation of the @-code is possible; perhaps you might hit the nail on the head on a subpoint here and there regarding some less-than-exemplary implementation).