Re: for or against equality, was Why are ambiguous grammars usually a bad idea?

From	gah4 <gah4@u.washington.edu>
Newsgroups	comp.compilers
Subject	Re: for or against equality, was Why are ambiguous grammars usually a bad idea?
Date	2022-01-04 13:26 -0800
Organization	Compilers Central
Message-ID	<22-01-014@comp.compilers> (permalink)
References	(2 earlier) <21-12-022@comp.compilers> <21-12-026@comp.compilers> <21-12-033@comp.compilers> <22-01-007@comp.compilers> <22-01-010@comp.compilers>

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On Tuesday, January 4, 2022 at 10:15:42 AM UTC-8, gah4 wrote:

(snip, our moderator wrote)

> [In original Dartmouth BASIC the LET was mandatory, but it was a considerably
> smaller and fully compiled language than the later dialects. On the other
> hand, PL/I made a fetish of nothing being a reserved word, e.g.
>
> IF IF = THEN THEN ELSE = BEGIN; ELSE END = IF;
>
> -John]

I never used any close to the original BASIC, but did use, for some time,
the HP TSB2000 version.  HP stores programs after tokenizing, so I suspect
that even if you don't put in LET, the tokenizer will add it.

As for PL/I, it borrowed many features from COBOL, but not the use
of reserved words.  For one, they wanted people not to have to know the whole
language, and not even the words.  Stories are that COBOL programmers always
keep the list of reserved words nearby, to avoid using them.

Counting from a recent IBM web page on their COBOL compiler, there are
over 400 reserved words, many common English words that people might
like to use.  Somehow out of 50 years of programming, I have managed
never to even type in and run a COBOL program, and especially not to
write one.

As for Fortran parsing, I do remember that WATFIV reserves the sequence
'FORMAT(' at the beginning of a statement for actual FORMAT statements.
You can't assign to elements of an array named FORMAT.  That might not
be so bad, except that Fortran 66, in its run-time format feature, requires the
format data to be in an array.  And the obvious name is FORMAT!
[COBOL doesn't have that many reserved words.  See https://www.ibm.com/docs/en/i/7.1?topic=list-reserved-words
Re FORMAT statements, WATFOR/FIV punted for some reason. It's not that
hard to tell a format statement from a statement like FORMAT(I5,A4) =
42 but I realize no sane programmer would do that. -John]

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