57 lines
1.4 KiB
Scheme
57 lines
1.4 KiB
Scheme
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(load "util.scm")
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(load "misc/amb.scm")
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(define nouns '(noun cat student professor class))
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(define verbs '(verb eats studies lectures sleeps))
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(define articles '(article the a))
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(define prepositions '(prep for to in by with))
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(define *unparsed* '())
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(define (parse-noun-phrase)
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(list 'noun-phrase
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(parse-word articles)
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(parse-word nouns)))
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(define (parse-word word-list)
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(require (not (null? *unparsed*)))
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(require (memq (car *unparsed*) (cdr word-list)))
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(let ((found-word (car *unparsed*)))
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(set! *unparsed* (cdr *unparsed*))
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(list (car word-list) found-word)))
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(define (parse input)
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(set! *unparsed* input)
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(let ((sent (parse-sentence)))
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(require (null? *unparsed*))
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sent))
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(define (parse-prepositional-phrase)
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(list 'prep-phrase
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(parse-word prepositions)
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(parse-noun-phrase)))
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(define (parse-sentence)
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(list 'sentence
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(parse-noun-phrase)
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(parse-verb-phrase)))
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(define (parse-verb-phrase)
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(define (maybe-extend verb-phrase)
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(amb verb-phrase
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(maybe-extend (list 'verb-phrase
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verb-phrase
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(parse-prepositional-phrase)))))
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(maybe-extend (parse-word verbs)))
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(display "\nex-4.45 - parse-sentence\n")
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;(sentence (noun-phrase (article the) (noun cat)) (verb eats))
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;'(The professor lectures to the student in the class with the cat)
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(display "\nex-4.46\n")
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