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vigenere.hs
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/
vigenere.hs
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import System.Environment
import Text.Read
lowers = ['a'..'z']
uppers = ['A'..'Z']
rotate :: Int -> Char -> Char
(rotate y) x
| (inside lowers) = (toEnum ((((fromEnum x)-(fromEnum 'a')+y) `mod` 26)+(fromEnum 'a'))::Char)
| (inside uppers) = (toEnum ((((fromEnum x)-(fromEnum 'A')+y) `mod` 26)+(fromEnum 'A'))::Char)
| otherwise = x
where inside = (elem x)
findLetterPos :: Char -> Int
findLetterPos x
| (inside lowers) = (fromEnum x)-(fromEnum 'a')
| (inside uppers) = (fromEnum x)-(fromEnum 'A')
| otherwise = 0
where inside = (elem x)
vigenere :: String -> String -> String
(vigenere shiftStr) shiftContents = zipWith rotate (cycle (map findLetterPos shiftStr)) shiftContents
main :: IO()
main = do
a <- getArgs --get shift word from command line args
ss <- getContents --get shift contents
let b = (head a)
putStr ((vigenere b) ss)