20 lines
458 B
Scheme
20 lines
458 B
Scheme
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;;; fat fibonacci function
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;;; this is "fat" because it uses only increments and decrements
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;;; for addition and subtraction (i.e., peano arithmetic).
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;;; note that fat+ is tail-recursive; this is how all looping is
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;;; performed in Scheme.
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(define fat+
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(lambda (x y)
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(if (zero? y)
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x
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(fat+ (1+ x) (1- y)))))
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(define fatfib
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(lambda (x)
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(if (< x 2)
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1
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(fat+ (fatfib (1- x)) (fatfib (1- (1- x)))))))
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