Scala quicksort

Here's a version of quicksort in Scala that I took from the excellent "Scala by Example" pdf from the scala website. The main algorithm is intact; I just thought it would be nice to get a print out of the steps being performed. So basically the program has been changed to include a few extra variables so that their value can be printed to the console. The unsorted input array has been hard-coded into the program just to avoid writing additional code to parse input arguments.

If you have scala installed, you can copy and paste the code to a file, compile it (scalac filename), run (scala compiledfilename) and see the output. Enjoy!

	object QuickSort {
	def sort(xs: Array[Int]): Array[Int] = {
	if (xs.length <= 1) xs
	else {
	val pivot = xs(xs.length / 2)
	val lessThanPivot = xs filter (pivot >)
	val equalToPivot = xs filter (pivot ==)
	val greaterThanPivot = xs filter (pivot <)
	println("Pivot for array [%s] is %d".format(xs.deep.mkString(" "),
	pivot))
	println("[%s] [%s] [%s]\n".format(lessThanPivot.deep.mkString(" "),
	equalToPivot.deep.mkString(" "),
	greaterThanPivot.deep.mkString(" ")))
	Array.concat(sort(lessThanPivot), equalToPivot, sort(greaterThanPivot))
	}
	}
	def main(args: Array[String]) {
	val inputArray = Array(10,9,8,3,7,6,5,4,3,2,1)
	println("Input Array : [%s]\n".format(inputArray.deep.mkString(" ")))
	println("Sorted Array: [%s]".format(sort(inputArray).deep.mkString(" ")))
	}
	}

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