2016 Update

Task/Caesar-cipher/Haskell/caesar-cipher-1.hs

@@ -0,0 +1,16 @@
+module Caesar (caesar, uncaesar) where
+
+import Data.Char
+
+caesar, uncaesar :: (Integral a) => a -> String -> String
+caesar k = map f
+    where f c = case generalCategory c of
+              LowercaseLetter -> addChar 'a' k c
+              UppercaseLetter -> addChar 'A' k c
+              _               -> c
+uncaesar k = caesar (-k)
+
+addChar :: (Integral a) => Char -> a -> Char -> Char
+addChar b o c = chr $ fromIntegral (b' + (c' - b' + o) `mod` 26)
+    where b' = fromIntegral $ ord b
+          c' = fromIntegral $ ord c