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/.env

@@ -0,0 +1,2 @@
+HERE=$(dirname "$1")
+(echo "$PATH" | grep "$HERE/bin" >/dev/null 2>&1) || export PATH="$HERE/bin:$PATH"

scala/official-by-example/.gitignore

@@ -0,0 +1,2 @@
+/bin/
+target/

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

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+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)
+  }
+}

scala/official-by-example/setup

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+#!/bin/bash
+
+set -e
+
+mkdir -p ./bin
+pushd ./bin
+curl -O 'https://raw.github.com/paulp/sbt-extras/master/sbt'
+chmod +x sbt
+popd
+./bin/sbt -sbt-create about