Lojban In General

Posted by pdf23ds on Tue 17 of Jun, 2008 16:43 GMT posts: 143

The PEG grammar has some left-recursion issues that could be taken
care of if I implement support for left recursion in my parser. On the
other hand, Rats!, which is what the grammar was initially written
toward, and *many* other PEG parsers/parsegens don't support real
left-recursion. So I don't know if we want the (eventual) official
grammar to use a non-standard feature of a tool. But it wouldn't be a
feature unique to my parser:

http://www.mail-archive.com/peg@lists.csail.mit.edu/msg00096.html

Left recursion is a very desirable feature to have, even though it's
hard to implement, so other parsers have it and will have it.
(Rewriting doesn't count (ever, I think), because it creates parse
trees that group things right-associatively even though they match the
same inputs.)

Another worry would be that you actually have to change PEG semantics
to do left recursion like this, and the change that needs to be made
isn't obvious or unique, so it could end up that different PEG parsers
implement different left recursion semantics that require slight
modifications to lojban's grammar to use with it, which would be less
than ideal.

Chris Capel
--
"What is it like to be a bat? What is it like to bat a bee? What is it
like to be a bee being batted? What is it like to be a batted bee?"
-- The Mind's I (Hofstadter, Dennet)

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