Phone Exercise.hs

mostPopularLetterWithCount :: String -> (Char, Int)
mostPopularLetterWithCount xs =
  swap . maximum . fmap swap . Map.toList . Map.fromListWith (+) $ [(x, 1) | x <- xs, not . isSpace $ x]

mostPopularWordWithCount :: String -> (String, Int)
mostPopularWordWithCount xs =
  swap . maximum . fmap swap . Map.toList . Map.fromListWith (+) $ [(x, 1) | x <- words xs]

4. What was the most popular letter for each message?

mostPopularLetter :: String -> Char
mostPopularLetter = fst. mostPopularLetterWithCount

mostPopularWord :: String -> String
mostPopularWord = fst . mostPopularWordWithCount

5. What was the most popular letter overall? What was the most
popular word?

coolestLtr :: [String] -> Char
coolestLtr = mostPopularLetter . concat

coolestWord :: [String] -> String
coolestWord = mostPopularWord . unwords