25 lines
529 B
Scheme
25 lines
529 B
Scheme
(module lex-plt-v200 mzscheme
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(require (lib "lex.ss" "parser-tools")
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(prefix : (lib "lex-sre.ss" "parser-tools")))
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(provide epsilon
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~
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(rename :* *)
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(rename :+ +)
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(rename :? ?)
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(rename :or :)
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(rename :& &)
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(rename :: @)
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(rename :~ ^)
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(rename :/ -))
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(define-lex-trans epsilon
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(syntax-rules ()
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((_) "")))
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(define-lex-trans ~
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(syntax-rules ()
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((_ re) (complement re)))))
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