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Date:	Mon, 16 Feb 2004 00:32:43 PST8
From:	"Lynn H. Maxson" <lmaxson@pacbell.net >
Reply-To:	scoug-programming@scoug.com
To:	< "scoug-programming@scoug.com" > scoug-programming@scoug.com >
Subject:	SCOUG-Programming: PL/I most important statement (was: call(TZ) ? - PL/I)

Content Type: text/plain

"So what? Assembler has been used for a lot of things, and
_it_ doesn't have "support" for such fancy operands. ..."

Well, obviously they couldn't get it to work and the project
was dropped. It was to use Fortran, not Fortran and
assembler. That would have killed it as a cross-platform
application as APL is.

REXX and APL assign data attributes, e.g. string or arithmetic,
dynamically based on its use in an assignment statement.
Begin-end of PL/I would allow that, Fortran has no such
equivalent. You don't have to get too deep into the parse
verb in REXX before you're way over what Fortran supports.
APL supports intermixing arithmetic, string, and logical
operators in an expression. Fortran does not.

"But once you've done it, just once, everybody else can then
make use of your algorithm."

Not if you can't do it even once.

"...I was thinking when I wrote that original message that we
should create a parser for your SL/I language (Steven Levine
had just explained YAC and LEXX [sp?] to me in a private
message) so we could "get the ball rolling" instead of arguing
the philosophy of who-what-when-where-why-how. ..."

Well, it is LEX & YACC. The answer is "no" with respect to
SL/I. Yes, you ought to check out your parsing methods
compared to them.

As SL/I syntax follows the same rules as PL/I you can write a
PL/I parser in any manner you desire. Frankly I would
probably start with understanding how it is done in LPEX (Live
Parsing EXecutive) that comes with your IBM PL/I compiler.
For my money LPEX is the starting point for developing the
Developer's Assistant, which is editor plus syntax analysis plus
semantic analysis plus logical organizer plus interpretive or
compile code generator plus automated test data generator.

On the other hand we do have versions of LEX & YACC for
OS/2. If the interest is there, maybe we should offer a
presentation on their use. Sounds like something Steven could
do from which we could all benefit.

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