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