19 lines
723 B
Racket
19 lines
723 B
Racket
#lang racket/base
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(provide parse-sequence)
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(require racket/match)
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(define-match-expander parse-sequence
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(syntax-rules ()
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[(_ predicate? to-list item-pat item-expr from-list target-pat)
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(? predicate? (app (lambda (v)
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(let loop ((inputs (to-list v)) (acc-rev '()))
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(match inputs
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['() (values #t (from-list (reverse acc-rev)))]
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[(cons untransformed remainder)
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(match untransformed
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[item-pat (loop remainder (cons item-expr acc-rev))]
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[_ (values #f #f)])])))
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#t target-pat))]))
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