+module Environment =
+struct
+ module Environment' = Map.Make (OrderedDomain)
+
+ include Environment'
+
+ let cons k v env =
+ try
+ let current = find k env in
+ let dsc, _ = v in
+ add k (v :: (List.filter (fun (dsc', _) -> dsc' <> dsc) current)) env
+ with Not_found ->
+ add k [v] env
+
+ let hd list_env =
+ try
+ map List.hd list_env
+ with Failure _ -> assert false
+
+ let fold_flatten f env base =
+ fold
+ (fun k l acc -> List.fold_right (fun v acc -> f k v acc) l acc)
+ env base
+
+end