What's the canonical way of getting an empty Iterator[A]? Iterator.empty
only wants to give me an Iterator[Nothing], which isn't quite what I'm
after.
The context is as the zero for a fold,
class DisjointUnion[A](family : List[Set[A]])
extends Set[A]
{
val size = ...
def contains(elem: A) = ...
def elements = family.foldLeft(???)(
(i : Iterator[A], s : Set[A]) => i ++ s.elements)
}
It feels like the '???' should be replaced by something like,
def elements = family.foldLeft(Iterator.empty[A])(
(i : Iterator[A], s : Set[A]) => i ++ s.elements)
where Iterator.empty[A] has the obvious definition,
def empty[A] : Iterator[A] = /* old Iterator.empty renamed */
Could this be done without too much breakage elsewhere in the Scala
libraries?
Cheers,
Miles
