setUnion_list :: (Ord b) => (a -> Set b) -> [a] -> Set b
setUnion_list f ts = foldl Set.union Set.empty $ map f ts
setUnion_list :: (Ord b) => (a -> Set b) -> [a] -> Set b
setUnion_list f ts = foldl Set.union Set.empty $ map f ts
setUnion_list f ts = foldl Set.union Set.empty $ map f ts