23 lines
899 B
Racket
23 lines
899 B
Racket
#lang scheme/base
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(provide string-append* string-join)
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(define string-append*
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(case-lambda [(strs) (apply string-append strs)] ; optimize common case
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[(s1 strs) (apply string-append s1 strs)]
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[(s1 s2 strs) (apply string-append s1 s2 strs)]
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[(s1 s2 s3 strs) (apply string-append s1 s2 s3 strs)]
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[(s1 s2 s3 s4 strs) (apply string-append s1 s2 s3 s4 strs)]
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[(str . strss) (apply apply string-append str strss)]))
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(require (only-in scheme/list add-between))
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(define (string-join strs sep)
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(cond [(not (and (list? strs) (andmap string? strs)))
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(raise-type-error 'string-join "list-of-strings" strs)]
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[(not (string? sep))
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(raise-type-error 'string-join "string" sep)]
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[(null? strs) ""]
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[(null? (cdr strs)) (car strs)]
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[else (apply string-append (add-between strs sep))]))
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