import qualified Data.List
import qualified Data.Map.Strict as Map
import Data.Char (isAsciiLower)

printRest :: [String] -> IO ()
printRest []     = return ()
printRest [x]    = putStrLn x
printRest (x:xs) = do
  putStr x
  putStr ", "
  printRest xs

printAnagram :: [String] -> IO ()
printAnagram []     = return ()
printAnagram (x:xs) = do
  putStr x
  putStr ": "
  printRest xs

main :: IO ()
main = do
  f <- readFile "/usr/share/dict/british-english-insane"
  let wordList = filter (all isAsciiLower) (lines f)
  let hashWords = [(hw, [w]) | w <- wordList, let hw = Data.List.sort w]
  let anagrams = Map.elems $ Map.fromListWith (\ x y -> y ++ x) hashWords
  let nonUniqueWords = Data.List.filter ((> 1) . length) anagrams
  mapM_ printAnagram $ Data.List.sortOn head nonUniqueWords