Partially complete IO chapter exercises
Inconveniently, I do not have the cipher code that I wrote from a previous chapter, and I'm not eager to reimplement it. TODO - Implement encrypt - Implement decrypt - Read all characters from STDIN
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scratch/haskell-programming-from-first-principles/io.hs
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scratch/haskell-programming-from-first-principles/io.hs
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module IOScratch where
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import qualified System.Environment as SE
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import qualified System.IO as SIO
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--------------------------------------------------------------------------------
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docs :: String
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docs = "Pass -e to encrypt and -d to decrypt."
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encryptStdin :: IO ()
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encryptStdin = do
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char <- SIO.hGetChar SIO.stdin
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-- encrypt char
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SIO.hPutStr SIO.stdout [char]
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decryptStdin :: IO ()
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decryptStdin = do
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char <- SIO.hGetChar SIO.stdin
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-- decrypt char
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SIO.hPutStr SIO.stdout [char]
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main :: IO ()
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main = do
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args <- SE.getArgs
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case args of
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[] ->
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putStrLn $ "You did not pass enough arguments. " ++ docs
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["-e"] ->
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encryptStdin
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["-d"] ->
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decryptStdin
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[x] ->
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putStrLn $ "You passed an unsupported option: " ++ x ++ ". " ++ docs
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_ ->
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putStrLn $ "You passed too many arguments. " ++ docs
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