29 lines
671 B
Text
29 lines
671 B
Text
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;; Calculation of Hofstadter's male and female sequences as a list of pairs
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(define (hofstadter-male-female n)
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(letrec ((female (lambda (n)
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(if (= n 0)
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1
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(- n (male (female (- n 1)))))))
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(male (lambda (n)
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(if (= n 0)
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0
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(- n (female (male (- n 1))))))))
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(let loop ((i 0))
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(if (> i n)
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'()
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(cons (cons (female i)
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(male i))
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(loop (+ i 1)))))))
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(hofstadter-male-female 8)
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(define (find-first func lst)
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(call-with-current-continuation
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(lambda (return-immediately)
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(for-each (lambda (x)
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(if (func x)
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(return-immediately x)))
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lst)
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#f)))
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