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Novice: How can I say "any superclass of universal A"

I play with the QuickSort example at the beginning of Scala as an example and try to adapt it to a generic type A, not just Ints.

Still working for me

def sort[A <: Ordered[A]](xs: Array[A])

That allows you to sortrun on all types that are reflexively ordered, likeRichBoolean .

But that I would also like to allow types Awhere they extend Ordered[B], where B is the superclass of A (so, for example, everything that extends Ordered[Any]).

How can I say that?

What I actually got is thanks to agilesteel's answer :

case class X( i : Int ) extends Ordered[X] {
  def compare( x : X ) = x.i - i
}

class Y( i : Int, j : Int ) extends X(i)

case class Z( i : Int ) extends Ordered[Any] {
  def compare( a : Any ) : Int = {
    if (! a.isInstanceOf[Z] ) 
      sys.error("whoops") 

    val z = a.asInstanceOf[Z]
    z.i - i
  }
}

object QuickSort {
  def main( args : Array[String] ) {
    val xs = Array( 3, 1, 2, 4 ) map X
    sort( xs );
    val ys = Array( 3, 1, 2, 4 ) map { i => new Y(i, -i) }
    sort[X,Y]( ys );
    val zs = Array( 3, 1, 2, 4 ) map Z
    sort[Any,Z]( zs );
  }
  def sort[B >: A, A <: Ordered[B]](xs: Array[A]) {
    def swap(i: Int, j: Int) {
      val t = xs(i); xs(i) = xs(j); xs(j) = t;
    }
    def sort1(l: Int, r: Int) {
      val pivot = xs((l + r) / 2)
        var i = 1; var j = r
      while (i <= j) {
        while (xs(i) < pivot) i += 1
        while (xs(j) > pivot) j -= 1
        if (i <= j) {
          swap(i, j)
          i += 1
          j += 1
        }
      }
      if (l < j) sort1(l, j)
      if (j < r) sort1(i, r)
    }
    sort1(0, xs.length - 1)
  }
}

, RichLong RichBoolean , Ordered ( Ordered[Long] Ordered[Boolean]).

+5
2

- ?

def sort[B >: A, A <: Ordered[B]](xs: Array[B])
+7

, , - , Ordered, . ( ) Ordered, . :

def sort[A <% Ordered[A]](xs: Array[A]) = ...

<% - , def sort(xs: Array[A])(implicit cv: A => Ordered[A]) = .... , , , .

+1

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