15 lines
376 B
Scheme
15 lines
376 B
Scheme
(define (accumulate op initial sequence)
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(if (null? sequence)
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initial
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(op (car sequence)
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(accumulate op initial (cdr sequence)))))
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(define (map p sequence)
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(accumulate (lambda (x y) (cons (p x) y)) '() sequence))
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(define (append seq1 seq2)
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(accumulate cons seq2 seq1))
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(define (length sequence)
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(accumulate (lambda (x y) (+ 1 y)) 0 sequence))
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