{- A grammar with an unreachable nonterminal symbol (`y'). -} module Dead where type Terminal = Char type Result = [] %{ Terminal = 'a' | 'b' | 'c' | 'd'; Nonterminal = s | x | y; s : x, 'a'; | 'b'; x : 'c'; y : 'd'; -- unreachable }% frown ts = fail "syntax error"