import Data.List

data Pieza = Peon|Caballo|Alfil|Torre|Dama|Rey deriving (Enum)
data Color = Blanco|Negro deriving (Enum)
data Trebejo = (Pieza, Color)




$ ghc chess.hs
[1 of 1] Compiling Main             ( chess.hs, chess.o )

chess.hs:5:16: error: Illegal binding of built-in syntax: (,)
  |
5 | data Trebejo = (Pieza, Color)
  |                ^^^^^^^^^^^^^^
[haroldo@semiosis haskell]$