Simplifiy anagram

anagram/src/Anagram.hs

@@ -4,13 +4,8 @@ import qualified Data.Char as C
 import qualified Data.List as L
 
 anagramsFor :: String -> [String] -> [String]
-anagramsFor xs xss = [x | x <- xss, let s = toUpper x, s /= ys && freq s == zs]
+anagramsFor xs xss = [x | x <- xss, let s = toUpper x, s /= ys && L.sort s == zs]
   where
+    toUpper = map C.toUpper
     ys = toUpper xs
-    zs = freq ys
-
-toUpper :: String -> String
-toUpper = map C.toUpper
-
-freq :: String -> [(Char, Int)]
-freq xs = map (\a -> (head a, length a)) $ L.group $ L.sort xs
+    zs = L.sort ys