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000011_icon-group-sender _Mon Aug 22 12:08:36 1994.msg
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1995-02-09
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Received: by cheltenham.cs.arizona.edu; Mon, 22 Aug 1994 13:04:18 MST
To: icon-group-l@cs.arizona.edu
Date: Mon, 22 Aug 94 12:08:36 EDT
From: dburton@salzo.cary.nc.us (David Burton)
Message-Id: <21VgRc6w165w@salzo.Cary.NC.US>
Organization: SalzoBoard BBS * 919-481-3787
Sender: icon-group-request@cs.arizona.edu
References: <330a3u$3vq@shum.cc.huji.ac.il>
Subject: Re: Simple syntax? A definition?
Errors-To: icon-group-errors@cs.arizona.edu
mslamm@pluto.cc.huji.ac.il (Zvi Lamm) writes:
> It appears to me that what counts is simplicity.
Agreed.
> A simple syntax would be
> one that can easaly be built (NOT parsed) by programs
^^^^^^^^^^^^
No. Any language is easily emitted by programs. A simple syntax must
also be easily parsed.
> It would also be easy for
> humans (that's us!) to learn and use.
Right. And that means excluding things that add to the learning curve
but do nothing for the expressive power of the language: like precedence,
and (less importantly) multiple, independent global name spaces.
The language should also be easy to read; that is, easy for a human to
parse, as well as for a machine.
> Does anyone have suggestions on how to define this in a more mathematical
> or precise way?
For readability, it should be top-down recursive-descent (LL) parsable.
> I thought about YACC clauses/sentence. But I am not sure
> it's enough because the YACC approach narrows you down to LALR.
The problem is not that YACC parsability limits what you can parse, but,
rather, that it does not limit it ENOUGH! A simple language is not just
LR or LALR parsable, it is also LL parsable. Otherwise, the reader of
the language has to "look ahead" and read language tokens without/before
knowing what is being specified.
Out of consideration for the *humans* that have to read and write the
languages, no language should be designed that is not LL (top-down)
parsable.
-Dave Burton <dburton@salzo.cary.nc.us>
For my PGP public key, finger dburton@cybernetics.net