Ejercicio deletreador en Haskell

deletreador.hs

getLetter :: [Char] -> [Char]
getLetter word =
  take 1 word

createSinglePhrase :: [Char] -> [Char]
createSinglePhrase word =
  getLetter word ++ " is for " ++ word

createPhrase :: [Char] -> [[Char]] -> [Char]
createPhrase word lst =
  if ( length lst == 1 )
    then createSinglePhrase word ++ ", and "
    else createSinglePhrase word ++ ", "

deletreador :: [[Char]] -> [Char]
deletreador words
  | words == [] = ""
  | length words == 1 = createSinglePhrase (head words)
  | otherwise = let x:xs = words in createPhrase x xs ++ deletreador xs