panagram

import Data.Char (isAlpha, toLower)
import qualified Data.Set as Set

totalLetters :: Int
totalLetters = 26

isPangram :: String -> Bool
isPangram text =
  let letters = Set.fromList [toLower ch | ch <- text, isAlpha ch]
  in Set.size letters == totalLetters


main :: IO()
main = do
  print $ isPangram "The quick brown fox jumps over the lazy dog."