concrete TicketEng of Ticket = { lincat Request, Station = Str ; lin Ticket X Y = ((("I" ++ ("would like" | "want") ++ "to get" | ("may" | "can") ++ "I get" | "can you give me" | []) ++ "a ticket") | []) ++ "from" ++ X ++ "to" ++ Y ++ ("please" | []) ; Hamburg = "Hamburg" ; Paris = "Paris" ; }