20 lines
618 B
Racket
20 lines
618 B
Racket
#lang planet dyoo/whalesong/cs019
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(define web-colors
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(shared ([W (cons "white" G)]
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[G (cons "grey" W)])
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W))
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(check-expect (first web-colors) "white")
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(check-expect (second web-colors) "grey")
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(check-expect (third web-colors) "white")
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(check-expect (fourth web-colors) "grey")
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(check-expect (fifth web-colors) "white")
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(check-expect (sixth web-colors) "grey")
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(check-expect (seventh web-colors) "white")
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(check-expect (eighth web-colors) "grey")
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(check-expect (equal? (rest web-colors) (rest (rest (rest web-colors)))) true)
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(check-expect (eq? (rest web-colors) (rest (rest (rest web-colors)))) true)
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