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22 lines
805 B
Racket
22 lines
805 B
Racket
#lang typed/racket/base
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(require typed/sugar/define "coerce.rkt")
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(define/typed+provide (starts-with? str starter)
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(Stringish Stringish -> Boolean)
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(let ([str (->string str)]
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[starter (->string starter)])
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(and (<= (string-length starter) (string-length str))
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(equal? (substring str 0 (string-length starter)) starter))))
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(define/typed+provide (ends-with? str ender)
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(Stringish Stringish -> Boolean)
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(let ([str (->string str)]
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[ender (->string ender)])
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(and (<= (string-length ender) (string-length str))
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(equal? (substring str (- (string-length str) (string-length ender)) (string-length str)) ender))))
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(define/typed+provide (capitalized? str)
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(Stringish -> Boolean)
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(let ([str (->string str)])
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(char-upper-case? (car (string->list str)))))
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