21 lines
456 B
Racket
21 lines
456 B
Racket
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#lang racket/base
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;; List utilities :-(
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(provide replacef)
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(require racket/list)
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(define (replacef lst finder replacer)
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(define-values (head tail) (splitf-at lst (lambda (e) (not (finder e)))))
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(if (null? tail)
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head
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(append head
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(replacer (car tail))
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(cdr tail))))
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(module+ test
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(require rackunit)
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(check-equal? (replacef '(1 2 3 4 5) even? (lambda (n) (list n n n)))
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'(1 2 2 2 3 4 5)))
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