Hi Doug, > What's the best way to handle Definite Clause Grammar syntax in pilog? > ... > So, I'm hoping for some pilog rules or a macro maybe that can handle > the --> (or equivalent) of DCG in pilog :-)
I don't fully understand the context or purpose, but http://en.wikipedia.org/wiki/Definite_clause_grammar says that "DCG notation is just syntactic sugar for normal definite clauses in Prolog". So you can write a function 'dcg' which does the necessary translation. I would simply call 'be' here, using 'macro' because 'be' doesn't evaluate its arguments (i.e. is a FEXPR): (de dcg CL (macro (be ^(if (pair (cadr CL)) (list (car CL) (list (cons (caadr CL) '@A) '@A)) (cons (car CL) '("@In" "@Out") (let Vars (make (link "@In") (for (I . @) (cddr CL) (link (pack "@" I)) ) (link "@Out") ) (mapcar list (cdr CL) Vars (cdr Vars) ) ) ) ) ) ) ) With that, the example in Wikipedia could be written as (dcg sentence nounPhrase verbPhrase) (dcg nounPhrase det noun) (dcg verbPhrase verb nounPhrase) (dcg det [the]) (dcg det [a]) (dcg noun [cat]) (dcg noun [bat]) (dcg verb [eats]) This expands to : (rules 'sentence 'nounPhrase 'verbPhrase 'det 'noun 'verb) 1 (be sentence ("@In" "@Out") (nounPhrase "@In" "@1") (verbPhrase "@1" "@Out")) 1 (be nounPhrase ("@In" "@Out") (det "@In" "@1") (noun "@1" "@Out")) 1 (be verbPhrase ("@In" "@Out") (verb "@In" "@1") (nounPhrase "@1" "@Out")) 1 (be det ((the . @A) @A)) 2 (be det ((a . @A) @A)) 1 (be noun ((cat . @A) @A)) 2 (be noun ((bat . @A) @A)) 1 (be verb ((eats . @A) @A)) -> verb Does this help? Cheers, - Alex -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
