Enumeración de los números enteros

3 Comentarios

1. Haskell

   enteros :: [Int] enteros = [0] ++ concat[[i,-i] | i<- [1..]] prop_enteros :: Int -> Property prop_enteros n = n > 0 ==> enteros !! n == (1-((2*n +1)*((-1)^n))) `div` 4

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   enteros :: [Int] enteros = [0] ++ concat[[i,-i] | i<- [1..]]   prop_enteros :: Int -> Property prop_enteros n =     n > 0 ==> enteros !! n == (1-((2*n +1)*((-1)^n))) `div` 4

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2. y por que no directamente:

   Haskell

   enteros :: [Int] enteros = map (\n -> (1-((2*n +1)*((-1)^n))) `div` 4) [0..]

   1 2	enteros :: [Int] enteros = map (\n -> (1-((2*n +1)*((-1)^n))) `div` 4) [0..]

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3. Haskell

   import Test.QuickCheck enteros :: [Int] enteros = [x | x <- concat (agrupa [[0,-1..],[1..]])] agrupa :: Eq a => [[a]] -> [[a]] agrupa [] = [] agrupa xss | elem [] xss = [] | otherwise = map head xss : agrupa (map tail xss) prop_enteros :: Int -> Property prop_enteros n = n > 0 ==> enteros !! n == (1 - (2 * n + 1) * (-1)^n) `div` 4 -- La comprobación es -- λ> quickCheckWith (stdArgs {maxSize=7}) prop_enteros -- +++ OK, passed 100 tests

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   import Test.QuickCheck   enteros :: [Int] enteros = [x | x <- concat (agrupa [[0,-1..],[1..]])]   agrupa :: Eq a => [[a]] -> [[a]] agrupa []  = [] agrupa xss | elem [] xss = []            | otherwise   = map head xss : agrupa (map tail xss)   prop_enteros :: Int -> Property prop_enteros n = n > 0 ==> enteros !! n == (1 - (2 * n + 1) * (-1)^n) `div` 4   -- La comprobación es --    λ> quickCheckWith (stdArgs {maxSize=7}) prop_enteros --    +++ OK, passed 100 tests

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