Una función rápida ( O(n) ) de los números de Fibonacci basada en evaluación perezosa y listas infinitas

Detalles por explicar...

Prelude> let fibs = 1:1:[a | a <- zipWith (+) fibs (tail (fibs))] in fibs!!1
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Prelude> let fibs = 1:1:[a | a <- zipWith (+) fibs (tail (fibs))] in fibs!!2
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Prelude> let fibs = 1:1:[a | a <- zipWith (+) fibs (tail (fibs))] in fibs!!3
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Prelude> let fibs = 1:1:[a | a <- zipWith (+) fibs (tail (fibs))] in fibs!!4
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Prelude> let fibs = 1:1:[a | a <- zipWith (+) fibs (tail (fibs))] in fibs!!5
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Prelude> let fibs = 1:1:[a | a <- zipWith (+) fibs (tail (fibs))] in fibs!!6
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Prelude> let fibs = 1:1:[a | a <- zipWith (+) fibs (tail (fibs))] in fibs!!7
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Prelude> let fibs = 1:1:[a | a <- zipWith (+) fibs (tail (fibs))] in fibs!!8
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