September 2017 Update

Task/Middle-three-digits/Haskell/middle-three-digits.hs

@@ -1,17 +1,35 @@
-import Numeric
+mid3 :: Int -> Either String String
+mid3 n
+  | m < 100 = Left "is too small"
+  | even l = Left "has an even number of digits"
+  | otherwise = Right . take 3 $ drop ((l - 3) `div` 2) s
+  where
+    m = abs n
+    s = show m
+    l = length s
 
-mid3 :: Integral a => a -> Either String String
-mid3 n |   m < 100 = Left "is too small"
-       |    even l = Left "has an even number of digits"
-       | otherwise = Right . take 3 $ drop ((l-3) `div` 2) s
-  where m = abs n
-        s = showInt m ""
-        l = length s
-
-showMid3 :: Integer -> String
+showMid3 :: Int -> String
 showMid3 n = show n ++ ": " ++ either id id (mid3 n)
 
 main :: IO ()
-main = mapM_ (putStrLn . showMid3) [
-  123, 12345, 1234567, 987654321, 10001, -10001, -123, -100, 100, -12345,
-  1, 2, -1, -10, 2002, -2002, 0]
+main =
+  mapM_
+    (putStrLn . showMid3)
+    [ 123
+    , 12345
+    , 1234567
+    , 987654321
+    , 10001
+    , -10001
+    , -123
+    , -100
+    , 100
+    , -12345
+    , 1
+    , 2
+    , -1
+    , -10
+    , 2002
+    , -2002
+    , 0
+    ]