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Re: Why don't compiler writers adhere to the dragon book recommendation of one lexer rule for keywords and identifiers?

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On Saturday, June 25, 2022 at 9:41:32 AM UTC-7, Roger L Costello wrote:

(snip)

> Page 101-102 of the dragon book recommends having one lexer rule for both
> keyword and identifiers (symtab = symbol table):

(and our moderator says)
> [I think the answer to a lot of these questions contains the phrase "64K PDP-11." ...]

The lost art of small memory compilers.

Before the PDP-11 there were big computers like the IBM 704, where Fortran
originated, and when core was $1/bit or more.  (The 704 with core was an
upgrade from the 701, using CRTs for main memory.) Big ones had 32K
words, but I think the Fortran compiler ran in 8K or 16K words.

After big computers got bigger, then we had minicomputers like the PDP-11
and Data General Nova and Eclipse, and some others, with 32K or so bytes.

And when minicomputers got bigger, everything happened again with
microcomputers, and again compilers had to fit.  I do remember swapping
floppy disks for passes of a Fortran and Pascal compiler for MS-DOS 2.0.

Some years ago, the Hercules group was trying to get gcc running
on an emulated IBM S/370 running MVS, with an 8M region.
(Out of the 16M byte address space, MVS takes up about half.)
But you can't run gcc in 8M bytes.

When I remember S/370 and OS/VS2, the usual region was 300K,
which we thought was big.

And now, we can barely run a system with 4G main memory,
such as the Macbook Air that I am writing this on.

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Why don't compiler writers adhere to the dragon book recommendation of one lexer rule for keywords and identifiers? Roger L Costello <costello@mitre.org> - 2022-06-25 12:58 +0000
  Re: Why don't compiler writers adhere to the dragon book recommendation of one lexer rule for keywords and identifiers? gah4 <gah4@u.washington.edu> - 2022-06-25 13:01 -0700
    Re: Why don't compiler writers adhere to the dragon book recommendation of one lexer rule for keywords and identifiers? Kaz Kylheku <480-992-1380@kylheku.com> - 2022-06-26 06:17 +0000
    Re: Why don't compiler writers adhere to the dragon book recommendation of one lexer rule for keywords and identifiers? Hans-Peter Diettrich <DrDiettrich1@netscape.net> - 2022-06-26 10:20 +0200
  One lexer rule for keywords and identifiers Christopher F Clark <christopher.f.clark@compiler-resources.com> - 2022-06-26 00:09 +0300

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