Studying polyvariadicity in Haskell

Poly1.hs

{-# LANGUAGE FlexibleInstances #-}

class C a where
  -- Tipo Args -> Tipo Acumulador -> C a
  boom :: String -> a

-- |Tipo final
instance C String where
  boom = id

-- instance C a => C (String -> a) where
--   boom acc a = boom (acc ++ " " ++ a)

instance (Show x, C a) => C (x -> a) where
  boom acc a =  boom (acc ++ " " ++ show a)

kaboom :: (C a, Show x) => x -> a
kaboom = boom ""

main :: IO ()
main = do
  putStrLn $ boom "asdfs" True (Just 'c') 23242
  putStrLn $ boom "asasdlf" "dlskfs"
  putStrLn $ kaboom "asasdlf" "dlskfs" True