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* [TUHS] [tuhs] Dennis Ritchie's couch
@ 2021-05-26  0:12 Nelson H. F. Beebe
  2021-05-26  0:37 ` Rob Pike
  2021-05-26  4:10 ` Avindra G
  0 siblings, 2 replies; 8+ messages in thread
From: Nelson H. F. Beebe @ 2021-05-26  0:12 UTC (permalink / raw)
  To: The Unix Heritage Society mailing list

The last article of the latest issue of the Communications of the ACM
that appeared electronically earlier today is a brief interview with
this year's ACM Turing Award winners, Al Aho and Jeff Ullman.

The article is

        Last byte: Shaping the foundations of programming languages
        https://doi.org/10.1145/3460442
        Comm. ACM 64(6), 120, 119, June 2021.

and it includes a picture of the two winners sitting on Dennis
Ritchie's couch.

I liked this snippet from Jeff Ullman, praising fellow list member
Steve Johnson's landmark program, yacc:

>> ...
>> At the time of the first Fortran compiler, it took several
>> person-years to write a parser.  By the time yacc came around, 
>> you could do it in an afternoon.
>> ...

-------------------------------------------------------------------------------
- Nelson H. F. Beebe                    Tel: +1 801 581 5254                  -
- University of Utah                    FAX: +1 801 581 4148                  -
- Department of Mathematics, 110 LCB    Internet e-mail: beebe@math.utah.edu  -
- 155 S 1400 E RM 233                       beebe@acm.org  beebe@computer.org -
- Salt Lake City, UT 84112-0090, USA    URL: http://www.math.utah.edu/~beebe/ -
-------------------------------------------------------------------------------

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [TUHS] [tuhs] Dennis Ritchie's couch
  2021-05-26  0:12 [TUHS] [tuhs] Dennis Ritchie's couch Nelson H. F. Beebe
@ 2021-05-26  0:37 ` Rob Pike
  2021-05-26  3:03   ` Larry McVoy
  2021-05-26  5:13   ` arnold
  2021-05-26  4:10 ` Avindra G
  1 sibling, 2 replies; 8+ messages in thread
From: Rob Pike @ 2021-05-26  0:37 UTC (permalink / raw)
  To: Nelson H. F. Beebe; +Cc: The Unix Heritage Society mailing list

[-- Attachment #1: Type: text/plain, Size: 1493 bytes --]

And today, we understand parsing so well we don't need yacc.

-rob


On Wed, May 26, 2021 at 10:20 AM Nelson H. F. Beebe <beebe@math.utah.edu>
wrote:

> The last article of the latest issue of the Communications of the ACM
> that appeared electronically earlier today is a brief interview with
> this year's ACM Turing Award winners, Al Aho and Jeff Ullman.
>
> The article is
>
>         Last byte: Shaping the foundations of programming languages
>         https://doi.org/10.1145/3460442
>         Comm. ACM 64(6), 120, 119, June 2021.
>
> and it includes a picture of the two winners sitting on Dennis
> Ritchie's couch.
>
> I liked this snippet from Jeff Ullman, praising fellow list member
> Steve Johnson's landmark program, yacc:
>
> >> ...
> >> At the time of the first Fortran compiler, it took several
> >> person-years to write a parser.  By the time yacc came around,
> >> you could do it in an afternoon.
> >> ...
>
>
> -------------------------------------------------------------------------------
> - Nelson H. F. Beebe                    Tel: +1 801 581 5254
>     -
> - University of Utah                    FAX: +1 801 581 4148
>     -
> - Department of Mathematics, 110 LCB    Internet e-mail:
> beebe@math.utah.edu  -
> - 155 S 1400 E RM 233                       beebe@acm.org
> beebe@computer.org -
> - Salt Lake City, UT 84112-0090, USA    URL:
> http://www.math.utah.edu/~beebe/ -
>
> -------------------------------------------------------------------------------
>

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^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [TUHS] [tuhs] Dennis Ritchie's couch
  2021-05-26  0:37 ` Rob Pike
@ 2021-05-26  3:03   ` Larry McVoy
  2021-05-26  4:02     ` Rob Pike
  2021-05-26  6:20     ` Bakul Shah
  2021-05-26  5:13   ` arnold
  1 sibling, 2 replies; 8+ messages in thread
From: Larry McVoy @ 2021-05-26  3:03 UTC (permalink / raw)
  To: Rob Pike; +Cc: The Unix Heritage Society mailing list

You do, I don't.  I'm not alone in my lack of understanding.

I think that all the things that yacc solved, Steve gets some kudos.
I've used it a bunch and I did not need to be as smart as you or
Steve to get the job done.

You getting past that is cool but it doesn't make his work less.

On Wed, May 26, 2021 at 10:37:45AM +1000, Rob Pike wrote:
> And today, we understand parsing so well we don't need yacc.
> 
> -rob
> 
> 
> On Wed, May 26, 2021 at 10:20 AM Nelson H. F. Beebe <beebe@math.utah.edu>
> wrote:
> 
> > The last article of the latest issue of the Communications of the ACM
> > that appeared electronically earlier today is a brief interview with
> > this year's ACM Turing Award winners, Al Aho and Jeff Ullman.
> >
> > The article is
> >
> >         Last byte: Shaping the foundations of programming languages
> >         https://doi.org/10.1145/3460442
> >         Comm. ACM 64(6), 120, 119, June 2021.
> >
> > and it includes a picture of the two winners sitting on Dennis
> > Ritchie's couch.
> >
> > I liked this snippet from Jeff Ullman, praising fellow list member
> > Steve Johnson's landmark program, yacc:
> >
> > >> ...
> > >> At the time of the first Fortran compiler, it took several
> > >> person-years to write a parser.  By the time yacc came around,
> > >> you could do it in an afternoon.
> > >> ...
> >
> >
> > -------------------------------------------------------------------------------
> > - Nelson H. F. Beebe                    Tel: +1 801 581 5254
> >     -
> > - University of Utah                    FAX: +1 801 581 4148
> >     -
> > - Department of Mathematics, 110 LCB    Internet e-mail:
> > beebe@math.utah.edu  -
> > - 155 S 1400 E RM 233                       beebe@acm.org
> > beebe@computer.org -
> > - Salt Lake City, UT 84112-0090, USA    URL:
> > http://www.math.utah.edu/~beebe/ -
> >
> > -------------------------------------------------------------------------------
> >

-- 
---
Larry McVoy            	     lm at mcvoy.com             http://www.mcvoy.com/lm 

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [TUHS] [tuhs] Dennis Ritchie's couch
  2021-05-26  3:03   ` Larry McVoy
@ 2021-05-26  4:02     ` Rob Pike
  2021-05-26  6:20     ` Bakul Shah
  1 sibling, 0 replies; 8+ messages in thread
From: Rob Pike @ 2021-05-26  4:02 UTC (permalink / raw)
  To: Larry McVoy; +Cc: The Unix Heritage Society mailing list

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In no way did I mean to diminish the work. Instead, I was admiring how our
knowledge of the field has continued to grow through the work they have
done.

-rob


On Wed, May 26, 2021 at 1:03 PM Larry McVoy <lm@mcvoy.com> wrote:

> You do, I don't.  I'm not alone in my lack of understanding.
>
> I think that all the things that yacc solved, Steve gets some kudos.
> I've used it a bunch and I did not need to be as smart as you or
> Steve to get the job done.
>
> You getting past that is cool but it doesn't make his work less.
>
> On Wed, May 26, 2021 at 10:37:45AM +1000, Rob Pike wrote:
> > And today, we understand parsing so well we don't need yacc.
> >
> > -rob
> >
> >
> > On Wed, May 26, 2021 at 10:20 AM Nelson H. F. Beebe <beebe@math.utah.edu
> >
> > wrote:
> >
> > > The last article of the latest issue of the Communications of the ACM
> > > that appeared electronically earlier today is a brief interview with
> > > this year's ACM Turing Award winners, Al Aho and Jeff Ullman.
> > >
> > > The article is
> > >
> > >         Last byte: Shaping the foundations of programming languages
> > >         https://doi.org/10.1145/3460442
> > >         Comm. ACM 64(6), 120, 119, June 2021.
> > >
> > > and it includes a picture of the two winners sitting on Dennis
> > > Ritchie's couch.
> > >
> > > I liked this snippet from Jeff Ullman, praising fellow list member
> > > Steve Johnson's landmark program, yacc:
> > >
> > > >> ...
> > > >> At the time of the first Fortran compiler, it took several
> > > >> person-years to write a parser.  By the time yacc came around,
> > > >> you could do it in an afternoon.
> > > >> ...
> > >
> > >
> > >
> -------------------------------------------------------------------------------
> > > - Nelson H. F. Beebe                    Tel: +1 801 581 5254
> > >     -
> > > - University of Utah                    FAX: +1 801 581 4148
> > >     -
> > > - Department of Mathematics, 110 LCB    Internet e-mail:
> > > beebe@math.utah.edu  -
> > > - 155 S 1400 E RM 233                       beebe@acm.org
> > > beebe@computer.org -
> > > - Salt Lake City, UT 84112-0090, USA    URL:
> > > http://www.math.utah.edu/~beebe/ -
> > >
> > >
> -------------------------------------------------------------------------------
> > >
>
> --
> ---
> Larry McVoy                  lm at mcvoy.com
> http://www.mcvoy.com/lm
>

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^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [TUHS] [tuhs] Dennis Ritchie's couch
  2021-05-26  0:12 [TUHS] [tuhs] Dennis Ritchie's couch Nelson H. F. Beebe
  2021-05-26  0:37 ` Rob Pike
@ 2021-05-26  4:10 ` Avindra G
  1 sibling, 0 replies; 8+ messages in thread
From: Avindra G @ 2021-05-26  4:10 UTC (permalink / raw)
  To: Nelson H. F. Beebe; +Cc: The Unix Heritage Society mailing list

[-- Attachment #1: Type: text/plain, Size: 1528 bytes --]

That is an impressive lotus posture (by Professor Ullman). What a fun
picture. Thanks for sharing.
avg


On Tue, May 25, 2021 at 8:20 PM Nelson H. F. Beebe <beebe@math.utah.edu>
wrote:

> The last article of the latest issue of the Communications of the ACM
> that appeared electronically earlier today is a brief interview with
> this year's ACM Turing Award winners, Al Aho and Jeff Ullman.
>
> The article is
>
>         Last byte: Shaping the foundations of programming languages
>         https://doi.org/10.1145/3460442
>         Comm. ACM 64(6), 120, 119, June 2021.
>
> and it includes a picture of the two winners sitting on Dennis
> Ritchie's couch.
>
> I liked this snippet from Jeff Ullman, praising fellow list member
> Steve Johnson's landmark program, yacc:
>
> >> ...
> >> At the time of the first Fortran compiler, it took several
> >> person-years to write a parser.  By the time yacc came around,
> >> you could do it in an afternoon.
> >> ...
>
>
> -------------------------------------------------------------------------------
> - Nelson H. F. Beebe                    Tel: +1 801 581 5254
>     -
> - University of Utah                    FAX: +1 801 581 4148
>     -
> - Department of Mathematics, 110 LCB    Internet e-mail:
> beebe@math.utah.edu  -
> - 155 S 1400 E RM 233                       beebe@acm.org
> beebe@computer.org -
> - Salt Lake City, UT 84112-0090, USA    URL:
> http://www.math.utah.edu/~beebe/ -
>
> -------------------------------------------------------------------------------
>

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^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [TUHS] [tuhs] Dennis Ritchie's couch
  2021-05-26  0:37 ` Rob Pike
  2021-05-26  3:03   ` Larry McVoy
@ 2021-05-26  5:13   ` arnold
  1 sibling, 0 replies; 8+ messages in thread
From: arnold @ 2021-05-26  5:13 UTC (permalink / raw)
  To: robpike, beebe; +Cc: tuhs

As a quite serious question, what do you use instead? Hand-written
recursive descent?  Some other form of machine generated parser?

Thanks,

Arnold

Rob Pike <robpike@gmail.com> wrote:

> And today, we understand parsing so well we don't need yacc.
>
> -rob
>
>
> On Wed, May 26, 2021 at 10:20 AM Nelson H. F. Beebe <beebe@math.utah.edu>
> wrote:
>
> > The last article of the latest issue of the Communications of the ACM
> > that appeared electronically earlier today is a brief interview with
> > this year's ACM Turing Award winners, Al Aho and Jeff Ullman.
> >
> > The article is
> >
> >         Last byte: Shaping the foundations of programming languages
> >         https://doi.org/10.1145/3460442
> >         Comm. ACM 64(6), 120, 119, June 2021.
> >
> > and it includes a picture of the two winners sitting on Dennis
> > Ritchie's couch.
> >
> > I liked this snippet from Jeff Ullman, praising fellow list member
> > Steve Johnson's landmark program, yacc:
> >
> > >> ...
> > >> At the time of the first Fortran compiler, it took several
> > >> person-years to write a parser.  By the time yacc came around,
> > >> you could do it in an afternoon.
> > >> ...
> >
> >
> > -------------------------------------------------------------------------------
> > - Nelson H. F. Beebe                    Tel: +1 801 581 5254
> >     -
> > - University of Utah                    FAX: +1 801 581 4148
> >     -
> > - Department of Mathematics, 110 LCB    Internet e-mail:
> > beebe@math.utah.edu  -
> > - 155 S 1400 E RM 233                       beebe@acm.org
> > beebe@computer.org -
> > - Salt Lake City, UT 84112-0090, USA    URL:
> > http://www.math.utah.edu/~beebe/ -
> >
> > -------------------------------------------------------------------------------
> >

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [TUHS] [tuhs] Dennis Ritchie's couch
  2021-05-26  3:03   ` Larry McVoy
  2021-05-26  4:02     ` Rob Pike
@ 2021-05-26  6:20     ` Bakul Shah
  2021-05-26  6:52       ` Rob Pike
  1 sibling, 1 reply; 8+ messages in thread
From: Bakul Shah @ 2021-05-26  6:20 UTC (permalink / raw)
  To: The Unix Heritage Society mailing list

Many existing programming languages do have a simple enough
syntax to make it easy to write a recursive descent parser for them
but not alll.

Handwritten recursive descent parsers are often LL(1) with may be 
a separate operator-precedence parsing for expressions.

If you are defining a new language syntax you can make sure parsing
is easy but not all languages are LL(1) (which is a subset of LALR(1),
which is a subset of LR(1), which is a subset of GLR). Handwritten
parsers for these more general grammars are bound to get more
complicated.

Even *we* understand parsing, writing a parser for some existing
languages  which grew "organically" can become tedious, or
complicated or adhoc. Often such languages have no well specified
grammar (the code is the specification!). A yacc grammar would help.

Often one writes a yacc grammar while a new language & its syntax
is evolving. Changing a yacc file is more localized & easier than fixing
up a handwritten parser. Even Go has such a grammar initially.

-- Bakul

> On May 25, 2021, at 8:03 PM, Larry McVoy <lm@mcvoy.com> wrote:
> 
> You do, I don't.  I'm not alone in my lack of understanding.
> 
> I think that all the things that yacc solved, Steve gets some kudos.
> I've used it a bunch and I did not need to be as smart as you or
> Steve to get the job done.
> 
> You getting past that is cool but it doesn't make his work less.
> 
> On Wed, May 26, 2021 at 10:37:45AM +1000, Rob Pike wrote:
>> And today, we understand parsing so well we don't need yacc.
>> 
>> -rob
>> 
>> 
>> On Wed, May 26, 2021 at 10:20 AM Nelson H. F. Beebe <beebe@math.utah.edu>
>> wrote:
>> 
>>> The last article of the latest issue of the Communications of the ACM
>>> that appeared electronically earlier today is a brief interview with
>>> this year's ACM Turing Award winners, Al Aho and Jeff Ullman.
>>> 
>>> The article is
>>> 
>>>        Last byte: Shaping the foundations of programming languages
>>>        https://doi.org/10.1145/3460442
>>>        Comm. ACM 64(6), 120, 119, June 2021.
>>> 
>>> and it includes a picture of the two winners sitting on Dennis
>>> Ritchie's couch.
>>> 
>>> I liked this snippet from Jeff Ullman, praising fellow list member
>>> Steve Johnson's landmark program, yacc:
>>> 
>>>>> ...
>>>>> At the time of the first Fortran compiler, it took several
>>>>> person-years to write a parser.  By the time yacc came around,
>>>>> you could do it in an afternoon.
>>>>> ...
>>> 
>>> 
>>> -------------------------------------------------------------------------------
>>> - Nelson H. F. Beebe                    Tel: +1 801 581 5254
>>>    -
>>> - University of Utah                    FAX: +1 801 581 4148
>>>    -
>>> - Department of Mathematics, 110 LCB    Internet e-mail:
>>> beebe@math.utah.edu  -
>>> - 155 S 1400 E RM 233                       beebe@acm.org
>>> beebe@computer.org -
>>> - Salt Lake City, UT 84112-0090, USA    URL:
>>> http://www.math.utah.edu/~beebe/ -
>>> 
>>> -------------------------------------------------------------------------------
>>> 
> 
> -- 
> ---
> Larry McVoy            	     lm at mcvoy.com             http://www.mcvoy.com/lm 


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [TUHS] [tuhs] Dennis Ritchie's couch
  2021-05-26  6:20     ` Bakul Shah
@ 2021-05-26  6:52       ` Rob Pike
  0 siblings, 0 replies; 8+ messages in thread
From: Rob Pike @ 2021-05-26  6:52 UTC (permalink / raw)
  To: Bakul Shah; +Cc: The Unix Heritage Society mailing list

[-- Attachment #1: Type: text/plain, Size: 3673 bytes --]

I enjoy writing recursive descent parsers, and I enjoy the grammars that
result from such parsers when cleanly done.

I do agree though that if you grammar is being invented as you go, yacc can
be a boon. But in a sense, that's also it's biggest failing: it makes it
too easy to write bad grammars.

-rob


On Wed, May 26, 2021 at 4:22 PM Bakul Shah <bakul@iitbombay.org> wrote:

> Many existing programming languages do have a simple enough
> syntax to make it easy to write a recursive descent parser for them
> but not alll.
>
> Handwritten recursive descent parsers are often LL(1) with may be
> a separate operator-precedence parsing for expressions.
>
> If you are defining a new language syntax you can make sure parsing
> is easy but not all languages are LL(1) (which is a subset of LALR(1),
> which is a subset of LR(1), which is a subset of GLR). Handwritten
> parsers for these more general grammars are bound to get more
> complicated.
>
> Even *we* understand parsing, writing a parser for some existing
> languages  which grew "organically" can become tedious, or
> complicated or adhoc. Often such languages have no well specified
> grammar (the code is the specification!). A yacc grammar would help.
>
> Often one writes a yacc grammar while a new language & its syntax
> is evolving. Changing a yacc file is more localized & easier than fixing
> up a handwritten parser. Even Go has such a grammar initially.
>
> -- Bakul
>
> > On May 25, 2021, at 8:03 PM, Larry McVoy <lm@mcvoy.com> wrote:
> >
> > You do, I don't.  I'm not alone in my lack of understanding.
> >
> > I think that all the things that yacc solved, Steve gets some kudos.
> > I've used it a bunch and I did not need to be as smart as you or
> > Steve to get the job done.
> >
> > You getting past that is cool but it doesn't make his work less.
> >
> > On Wed, May 26, 2021 at 10:37:45AM +1000, Rob Pike wrote:
> >> And today, we understand parsing so well we don't need yacc.
> >>
> >> -rob
> >>
> >>
> >> On Wed, May 26, 2021 at 10:20 AM Nelson H. F. Beebe <
> beebe@math.utah.edu>
> >> wrote:
> >>
> >>> The last article of the latest issue of the Communications of the ACM
> >>> that appeared electronically earlier today is a brief interview with
> >>> this year's ACM Turing Award winners, Al Aho and Jeff Ullman.
> >>>
> >>> The article is
> >>>
> >>>        Last byte: Shaping the foundations of programming languages
> >>>        https://doi.org/10.1145/3460442
> >>>        Comm. ACM 64(6), 120, 119, June 2021.
> >>>
> >>> and it includes a picture of the two winners sitting on Dennis
> >>> Ritchie's couch.
> >>>
> >>> I liked this snippet from Jeff Ullman, praising fellow list member
> >>> Steve Johnson's landmark program, yacc:
> >>>
> >>>>> ...
> >>>>> At the time of the first Fortran compiler, it took several
> >>>>> person-years to write a parser.  By the time yacc came around,
> >>>>> you could do it in an afternoon.
> >>>>> ...
> >>>
> >>>
> >>>
> -------------------------------------------------------------------------------
> >>> - Nelson H. F. Beebe                    Tel: +1 801 581 5254
> >>>    -
> >>> - University of Utah                    FAX: +1 801 581 4148
> >>>    -
> >>> - Department of Mathematics, 110 LCB    Internet e-mail:
> >>> beebe@math.utah.edu  -
> >>> - 155 S 1400 E RM 233                       beebe@acm.org
> >>> beebe@computer.org -
> >>> - Salt Lake City, UT 84112-0090, USA    URL:
> >>> http://www.math.utah.edu/~beebe/ -
> >>>
> >>>
> -------------------------------------------------------------------------------
> >>>
> >
> > --
> > ---
> > Larry McVoy                        lm at mcvoy.com
> http://www.mcvoy.com/lm
>
>

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^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2021-05-26  6:53 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-05-26  0:12 [TUHS] [tuhs] Dennis Ritchie's couch Nelson H. F. Beebe
2021-05-26  0:37 ` Rob Pike
2021-05-26  3:03   ` Larry McVoy
2021-05-26  4:02     ` Rob Pike
2021-05-26  6:20     ` Bakul Shah
2021-05-26  6:52       ` Rob Pike
2021-05-26  5:13   ` arnold
2021-05-26  4:10 ` Avindra G

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