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This is kind of a soft question, but in the following code, there's a lot of duplication in the section marked "caesar ciphers." What's the "Haskell" way to deal with this? Should I make a higher order function? I thought about that, but I don't know what makes sense. Is there a "cipher" type that I could define for making ciphers? Also, I know it may appear a little bit overengineered, in the sense that I'm doing the same error checking in two places, but I think it makes sense from the perspective of what each of the functions "means." Suggestions? import Data.Char import Control.Applicative import Control.Monad import Math.NumberTheory.Powers --Helpers extendedGcd::Integer->Integer->(Integer, Integer) extendedGcd a b | r == 0 = (0, 1) | otherwise = (y, x - (y * d)) where (d, r) = a `divMod` b (x, y) = extendedGcd b r modularInverse::Integer->Integer->Maybe Integer modularInverse n b | relativelyPrime n b = Just . fst $ extGcd n b | otherwise = Nothing where extGcd = extendedGcd relativelyPrime::Integer->Integer->Bool relativelyPrime m n = gcd m n == 1 textToDigits::String->[Integer] textToDigits = map (\x->toInteger (ord x - 97)) digitsToText::[Integer]->String digitsToText = map (\x->chr (fromIntegral x + 97)) --Caesar Ciphers caesarEncipher::Integer->Integer->Integer->Maybe Integer caesarEncipher r s p | relativelyPrime r 26 = Just $ mod (r * p + s) 26 | otherwise = Nothing caesarDecipher::Integer->Integer->Integer->Maybe Integer caesarDecipher r s c | relativelyPrime r 26 = mod <$> ((*) <$> q <*> pure (c - s)) <*> pure 26 | otherwise = Nothing where q = modularInverse r 26 caesarEncipherString::Integer->Integer->String->Maybe String caesarEncipherString r s

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