WithFilter

class WithFilter(p: A => Boolean)

We need a whole WithFilter class to honor the "doesn't create a new collection" contract even though it seems unlikely to matter much in a collection with max size 1.

class Object
trait Matchable
class Any

Value members

Concrete methods

def flatMap[B](f: A => Option[B]): Option[B]
def foreach[U](f: A => U): Unit
def map[B](f: A => B): Option[B]