Ben's solution

src/main/scala/internal/ForLoop.scala

@@ -1,7 +1,7 @@
 package internal
 
 /**
- * the loop body should execute 5 times and print:
+ * the loop body should execute 10 times and print:
  * 0
  * 2
  * 4
@@ -11,7 +11,13 @@ package internal
 
 object ForLoop extends App {
 
-  // define the new control-flow structure here 
+  def for_loop(initializer: ⇒Unit)(condition: ⇒Boolean)(increment: ⇒Unit)(body: ⇒Unit) = {
+    initializer
+    while (condition) {
+      body
+      increment
+    }
+  }
 
   var i = 0;
   for_loop(i = 0)(i < 10)(i += 2) {

src/main/scala/internal/LoopUntil.scala

@@ -10,7 +10,11 @@ package internal
  */
 object LoopUntil extends App {
 
-  // define the new control-flow structure here
+  def loop_until(condition: ⇒Boolean)(body: ⇒Unit) = {
+    while (!condition) {
+      body
+    } 
+  }
 
   var i = 0
 

src/main/scala/internal/RepeatUntil.scala

@@ -11,13 +11,33 @@ package internal
 
 object RepeatUntil extends App {
 
-  // define the new control-flow structure here
+  class RepeatClass(body: ⇒Unit) {
+    def until(condition: ⇒Boolean) = {
+      do {
+        body
+      } while(!condition)
+    }
+  }
+
+  def repeat(body: ⇒Unit) = new RepeatClass(body)
+
+  /** 
+   *  Alternative definition, using a new feature -- implicit classes --
+   *  that was recently added to Scala
+   */
+  /*  implicit class repeat(body: ⇒Unit) {
+        def until(condition: ⇒Boolean) = {
+          do {
+            body
+          } while(!condition)
+      }
+  }*/
 
   var i = 0
   repeat  {
       if ( (i % 2) == 0 )
           println(i)
       i += 1
-  } until(i > 9)        
+  } until(i > 9)      
 }
 

src/main/scala/internal/WhileContinue.scala

@@ -11,7 +11,20 @@ package internal
 
 object WhileContinue extends App {
 
-  // define the new control-flow structures here
+  object ContinueException extends Exception
+
+  def continue = throw ContinueException
+
+  def while_c(condition: ⇒Boolean)(body: ⇒Unit): Unit = {
+    try {
+      while (condition) {
+        body
+      }
+    } catch {
+      case ContinueException ⇒ while_c(condition)(body)
+      case other: Exception ⇒ throw other
+    }
+  }
 
   var i = -1