Quick Sort, My Groovy Implementation

My Groovy Implementation for QuickSort:

	def quickSort(list) {
	/*Make sure there are at least 2 elements in the list*/
	if (list == null || list.size() < 2) {
	return list
	}
	/*break the list to three different groups
	group 1: with elements less than pivot
	group 2: with elements equal to pivot
	group 3: with elements greater than pivot */
	def partitions = list.groupBy { it <=> list[0] }.withDefault { [] }
	/* sort group 1 and 3 and merge them with group 3 */
	return quickSort(partitions[-1]) + partitions[0] + quickSort(partitions[1])
	}
	assert [] == quickSort([])
	assert [1] == quickSort([1])
	assert [1,5] == quickSort([5, 1])
	assert [1,2,3,4,5] == quickSort([5,1,4,3,2])

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