haskell - 引数の数が異なる Haskell 関数

Question

この関数をさまざまな数の引数で動作させるために、クラスを使用して Haskell 関数を作成しようとしています。

{-# Language FlexibleInstances #-}

class Titles a where
  titleTeX ::  String -> a

instance Titles String where
  titleTeX str = titleWithFrame 1 "%" "%" "%" [str]

instance  Titles (String -> String) where
  titleTeX str = (\s -> titleWithFrame 1 "%" "%" "%" (s:[str]))

titleWithFrame::Int -> String -> String -> String -> [String] -> String
titleWithFrame nb beg end com lstr =
  cadr++cont++cadr
    where
          cadr = concat $ replicate nb (beg++rempl++end++"\n")
          cont = concatMap (\s -> beg++" "++s++" "++end++"\n") lstr
          rempl = take long $ concat $ replicate long com
          long = (maximum $ map length lstr) + 2

この関数を ghci で試すと、次の結果が得られます。

ghci> putStr $ titleTeX "Line 1"
%%%%%%%%%%
% Line 1 %
%%%%%%%%%%
ghci> putStr $ titleTeX "Line 1" "Line 2"
%%%%%%%%%%
% Line 1 %
% Line 2 %
%%%%%%%%%%
ghci> putStr $ titleTeX "Line 1" "Line 2" "Line 3"

<interactive>:4:10: error:
    • No instance for (Main.Titles ([Char] -> [Char] -> String))
        arising from a use of ‘titleTeX’
        (maybe you haven't applied a function to enough arguments?)
    • In the second argument of ‘($)’, namely
        ‘titleTeX "Line 1" "Line 2" "Line 3"’
      In the expression: putStr $ titleTeX "Line 1" "Line 2" "Line 3"
      In an equation for ‘it’:
          it = putStr $ titleTeX "Line 1" "Line 2" "Line 3"

エラーの場所と、多変量関数が 2 つ以上の引数で機能しない理由がわかりません。

私のエラーがどこから来たのか知っていますか？関数を任意の数の引数で動作させる方法は?