June 2018 Update

Task/Semordnilap/Haskell/semordnilap.hs

@@ -1,10 +1,17 @@
 import qualified Data.Set as S
 
-semordnilaps = snd . foldl f (S.empty,[]) where
-	f (s,w) x | S.member (reverse x) s = (s, x:w)
-	          | otherwise = (S.insert x s, w)
+semordnilaps
+  :: (Ord a, Foldable t)
+  => t [a] -> [[a]]
+semordnilaps =
+  let f x (s, w)
+        | S.member (reverse x) s = (s, x : w)
+        | otherwise = (S.insert x s, w)
+  in snd . foldr f (S.empty, [])
 
-main=do	s <- readFile "unixdict.txt"
-	let l = semordnilaps (lines s)
-	print $ length l
-	mapM_ print $ map (\x->(x, reverse x)) $ take 5 l
+main :: IO ()
+main = do
+  s <- readFile "unixdict.txt"
+  let l = semordnilaps (lines s)
+  print $ length l
+  mapM_ (print . ((,) <*> reverse)) $ take 5 l