First quicksort version

although the tutorial did not have a class or object definition,
which is necessary according to sbt ...   hmmm.

scala/official-by-example/byx/build.sbt

@@ -0,0 +1,3 @@
+name := "byx"
+
+version := "0.1.0"

scala/official-by-example/byx/src/main/scala/sort.scala

@@ -0,0 +1,23 @@
+object sort {
+  def sort(xs: Array[Int]) {
+    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 = l; 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)
+  }
+}