Hey all,

I've found myself reaching for the following function a couple of times now, so I figured it might make a good addition.

  intersections :: Ord a => NonEmpty (Set a) -> Set a
  intersections (s :| ss) = Foldable.foldl' intersection s ss

In a similar vein, we may as well add the following newtype + instance combo:

  newtype Intersection a = Intersection { getIntersection :: Set a }

  instance (Ord a) => Semigroup (Intersection a) where
      (Intersection a) <> (Intersection b) = Intersection $ intersection a b
      stimes = stimesIdempotent

Would love to hear everyone's thoughts on this!

Thanks

Reed Mullanix