types : string -> (string * int) list
- load "rich_listTheory"; - itlist union (map types (ancestry "-")) []; > val it = [("one", 0), ("option", 1), ("num", 0), ("sum", 2), ("recspace", 1), ("prod", 2), ("list", 1), ("bool", 0), ("ind", 0), ("fun", 2)] : (string * int) list