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PartialOrdering assignment in the Scala library

I understand that it is a partial order from a mathematical point of view, but cannot see where and how PartialOrdering you can use a class from the Scala library. I looked through the entire standard library and there was only one use: it was expanded by Ordering. The same story for the main method tryCompareseems to be not used anywhere.

So, what benefits can I get if instead

case class Foo(x: Int, y: String)

val order = Ordering.by { foo => (foo.x, foo.y) }

I will implement a more appropriate instance for the domain:

object PartialFoo extends PartialOrdering[Foo] {
  def tryCompare(a: Foo, b: Foo): Option[Foo] = {
    if (a.x != b.x) None  // Doesn't make sense to compare foos with different xs
    else ???
  }
}

UPD . It also looks like with a return type Some[Int](not Option[Int]) and I can’t even use redefinition. Intentionally?

+4
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def doSomethingForPartiallyOrdered[T](t: T)(implicit po: PartialOrdering[T]) = _

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+1

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