Dígitos visibles y ocultos

3 Comentarios

1. Haskell

   import Data.Char import Data.Maybe import Control.Monad import Control.Applicative visible :: Char -> Maybe Char visible d = const d <$> guard (isDigit d) oculto :: Char -> Maybe Char oculto d = (const $ chr $ ord d - 49) <$> guard (d `elem` ['a'..'j']) numeroOculto :: String -> Maybe Integer numeroOculto = fmap fst . listToMaybe . reads . mapMaybe (\d -> visible d <|> oculto d)

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   import Data.Char import Data.Maybe import Control.Monad import Control.Applicative   visible :: Char -> Maybe Char visible d = const d <$> guard (isDigit d)   oculto :: Char -> Maybe Char oculto d = (const $ chr $ ord d - 49) <$> guard (d `elem` ['a'..'j'])   numeroOculto :: String -> Maybe Integer numeroOculto = fmap fst . listToMaybe . reads . mapMaybe (\d -> visible d <|> oculto d)

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2. Haskell

   import Data.Char numeroOculto :: String -> Maybe Integer numeroOculto xs | null (aux xs []) = Nothing | otherwise = Just (read (aux xs [])) where aux :: String -> String -> String aux [] ns = reverse ns aux (x:xs) ns | x `elem` ['0'..'9'] = aux xs (x:ns) | x `elem` ['a'..'j'] = aux xs ((traduccion x):ns) | otherwise = aux xs ns -- Lista donde se da la relación entre los caracteres. eq :: [(Char,Char)] eq = zip ['a'..'j'] ['0'..'9'] -- Función que traduce el valor de un caracter a su valor -- como caracter numérico. traduccion :: Char -> Char traduccion x = [y | y <- ['0'..'9'] , (x,y) `elem` eq] !! 0

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   import Data.Char   numeroOculto :: String -> Maybe Integer numeroOculto xs    | null (aux xs []) = Nothing    | otherwise                  = Just (read (aux xs []))    where      aux :: String -> String -> String      aux [] ns                           = reverse ns      aux (x:xs) ns | x `elem` ['0'..'9'] = aux xs (x:ns)                    | x `elem` ['a'..'j'] = aux xs ((traduccion x):ns)                    | otherwise           = aux xs ns -- Lista donde se da la relación entre los caracteres. eq :: [(Char,Char)] eq = zip ['a'..'j'] ['0'..'9'] -- Función que traduce el valor de un caracter a su valor -- como caracter numérico. traduccion :: Char -> Char traduccion x = [y | y <- ['0'..'9'] , (x,y) `elem` eq] !! 0

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3. Haskell

   import Data.Maybe (mapMaybe) import Text.Read (readMaybe) numeroOculto :: String -> Maybe Integer numeroOculto cs = readMaybe $ mapMaybe (`lookup` zs) cs where zs = zip "0123456789abcdefghij" "01234567890123456789"

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   import Data.Maybe (mapMaybe) import Text.Read  (readMaybe)   numeroOculto :: String -> Maybe Integer numeroOculto cs = readMaybe $ mapMaybe (`lookup` zs) cs     where zs = zip "0123456789abcdefghij"                    "01234567890123456789"

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