neric representation of a list to an actual list. This
-- function is inverse of 'fromList'. It may fail if constructors have
-- wrong names.
toList ∷ ListG a → Maybe [a]
toList (LEFT  (CONS "[]" UNIT))         = Just []
toList (RIGHT (CONS "
toList ∷ ListG a → Maybe [a]
toList (LEFT  (CONS "[]" UNIT))         = Just []
toList (LEFT  (CONS "[]" UNIT))         = Just []