User-oriented BNF "walker"?

Chuck Lutz <>
17 Jan 2003 23:07:53 -0500

          From comp.compilers

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User-oriented BNF "walker"? (Chuck Lutz) (2003-01-17)
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Re: User-oriented BNF "walker"? (Andreas Gieriet) (2003-01-21)
Re: User-oriented BNF "walker"? (2003-02-06)
Re: User-oriented BNF "walker"? (Rodney M. Bates) (2003-02-11)
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From: Chuck Lutz <>
Newsgroups: comp.compilers
Date: 17 Jan 2003 23:07:53 -0500
Organization: Compilers Central
Keywords: tools, parse, question
Posted-Date: 17 Jan 2003 23:07:52 EST

Hi folks,

I've just subscribed to this list and this is my first post.

I'm not a compiler theorist, but I routinely find that I need to refer
to BNF/EBNF specifications when using a language. It can be very
tricky to keep track of where I am when mentally traversing the tree
of possi- bilities. I often find myself writing out expansions by
hand so that I can figure out what I am allowed to type. What a mess!

Even in today's world of on-the-fly syntax checking tools, it can be
hard to figure out how to type a language construct when all you have
is an EBNF spec to go on. The autocheckers can only complain, they
cannot point the way. Scores of trial-and-error passes through
autochecks are really just a frustrating waste of time.

I am wondering if there is some sort of "interactive" tool out there
that can be used to incrementally build up syntactic structures. As I
wrote, I'm not a compiler theorist so I don't know if this is some
sort of theroet- ical no-no. Since I'm befuddled by the apparent lack
of such "seemingly easy to do" tools (i.e. the idea of interacting
with such a tool is very in- tuitive and easily imagined), perhaps it
is indeed a theoretical brick wall.

From what I'm told, some tools that behaved in some manner like this
appeared in the 80s but were abandoned due to difficulty of use. Is
this true? The only thing I've seen that comes close to this "dream"
is the structure building mechanism in the Alice 3D graphical
programming environment from CMU. I have considered that attempts from
the 80s may have "failed" due to the lack of today's comparatively
advanced GUI possibilities. Alice is impressive, IMO.

Any tips would be greatly appreciated, even if it's only "you're


/Chuck Lutz

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