diff --git a/examples/src/Color.jetl b/examples/src/Color.jetl
index 2c2c4278ff1..c4642656639 100644
--- a/examples/src/Color.jetl
+++ b/examples/src/Color.jetl
@@ -1,4 +1,4 @@
-enum class Color(val r, g, b : Int) {
+enum class Color(val r : Int , val g :Int , val b : Int) {
   RED : Color(255, 0, 0)
   GREEN : Color(0, 255, 0)
   BLUE : Color(0, 0, 255)
diff --git a/examples/src/Factories.jetl b/examples/src/Factories.jetl
index fa8d464897e..53d4b78ca33 100644
--- a/examples/src/Factories.jetl
+++ b/examples/src/Factories.jetl
@@ -3,10 +3,10 @@ class Foo(bar : Bar) {
     private val cache = HashMap<Bar, Foo>()
 
 // Factory method:
-    Foo() = Foo(null);
+    fun Foo() = Foo(null);
 
 // Factory method:
-    Foo(bar : Bar) = cache.cachedLookup(bar, this(bar))
+    fun Foo(bar : Bar) = cache.cachedLookup(bar, this(bar))
   }
 
   fun doFoo() {
@@ -16,7 +16,7 @@ class Foo(bar : Bar) {
 
 // To create an object of Foo
 val foo = Foo()
-or
+// or
 val foo = Foo(Bar())
 
 // Subclass (Foo must be marked as extendable/open, i.e. ont sealed)
@@ -24,7 +24,7 @@ class FooSub(S : String) : Foo() { // Delegates to Foo created as a result of th
 
 }
 
-extension Map<K, V>.cachedLookup(key : K, lazy value : V) : V {
+fun Map<K, V>.cachedLookup(key : K, lazy value : V) : V {
   var v = this[key]
   if (v == null) {
     v = value
diff --git a/examples/src/collections/IIterable.jetl b/examples/src/collections/IIterable.jetl
index 2ef19c0caed..5e69296338c 100644
--- a/examples/src/collections/IIterable.jetl
+++ b/examples/src/collections/IIterable.jetl
@@ -1,3 +1,3 @@
-interface class IIterable<out T> {
+virtual class IIterable<out T> {
   fun iterator() : IIterator<T>
 }
diff --git a/examples/src/collections/IIterator.jetl b/examples/src/collections/IIterator.jetl
index 2ec8bc66cae..faeb4d40a5c 100644
--- a/examples/src/collections/IIterator.jetl
+++ b/examples/src/collections/IIterator.jetl
@@ -1,4 +1,4 @@
-interface class IIterator<out T> {
+virtual class IIterator<out T> {
   fun next() : T
   val hasNext : Boolean
 
@@ -14,7 +14,7 @@ interface class IIterator<out T> {
     if (len == 0) return 0
 
     var count = 0;
-    for (i in [from .. from + length - 1]) {
+    for (i in from .. from + length - 1) {
       if (!hasNext)
         return count
       buffer[i] = next()
diff --git a/examples/src/collections/IList.jetl b/examples/src/collections/IList.jetl
index 70f1e2cfb2e..6daa67bac0f 100644
--- a/examples/src/collections/IList.jetl
+++ b/examples/src/collections/IList.jetl
@@ -1,4 +1,4 @@
-interface class IList<out T> : IIterable<T>, ISized {
+virtual class IList<out T> : IIterable<T>, ISized {
   [operator] fun get(index : Int) : T
   val isEmpty : Boolean
 }
\ No newline at end of file
diff --git a/examples/src/collections/IMutableIterable.jetl b/examples/src/collections/IMutableIterable.jetl
index a60bf71c95c..22b6e017d8e 100644
--- a/examples/src/collections/IMutableIterable.jetl
+++ b/examples/src/collections/IMutableIterable.jetl
@@ -1,3 +1,3 @@
-interface class IMutableIterable<out T> : IIterable<T> {
+virtual class IMutableIterable<out T> : IIterable<T> {
   fun mutableIterator() : IMutableIterator<T>
 }
\ No newline at end of file
diff --git a/examples/src/collections/IMutableIterator.jetl b/examples/src/collections/IMutableIterator.jetl
index 775980ccedc..51111049926 100644
--- a/examples/src/collections/IMutableIterator.jetl
+++ b/examples/src/collections/IMutableIterator.jetl
@@ -1,4 +1,4 @@
-interface class IMutableIterator<out T> : IIterator<T> {
+virtual class IMutableIterator<out T> : IIterator<T> {
   fun remove() : T
 
 /*
diff --git a/examples/src/collections/IMutableList.jetl b/examples/src/collections/IMutableList.jetl
index 2b308d8ca86..711f0d6bfc7 100644
--- a/examples/src/collections/IMutableList.jetl
+++ b/examples/src/collections/IMutableList.jetl
@@ -1,4 +1,4 @@
-interface class IMutableList<T> : IList<T>, IMutableIterable<T> {
+virtual class IMutableList<T> : IList<T>, IMutableIterable<T> {
   fun set(index : Int, value : T) : T
   fun add(index : Int, value : T)
   fun remove(index : Int) : T
diff --git a/examples/src/collections/IMutableSet.jetl b/examples/src/collections/IMutableSet.jetl
index aa4edbee412..eacb0d740ec 100644
--- a/examples/src/collections/IMutableSet.jetl
+++ b/examples/src/collections/IMutableSet.jetl
@@ -1,4 +1,4 @@
-interface class IMutableSet<T> : ISet<T>, IMutableIterable<T> {
+virtual class IMutableSet<T> : ISet<T>, IMutableIterable<T> {
   fun add(item : T) : Boolean
   fun remove(item : T) : Boolean
 }
\ No newline at end of file
diff --git a/examples/src/collections/ISet.jetl b/examples/src/collections/ISet.jetl
index 8c32364dcf9..bfe2753b8df 100644
--- a/examples/src/collections/ISet.jetl
+++ b/examples/src/collections/ISet.jetl
@@ -1,3 +1,3 @@
-interface class ISet<T> : IIterable<T>, ISized {
+virtual class ISet<T> : IIterable<T>, ISized {
   fun contains(item : T) : Boolean
 }
diff --git a/examples/src/collections/ISized.jetl b/examples/src/collections/ISized.jetl
index 0b724f702d5..9f12cb218b0 100644
--- a/examples/src/collections/ISized.jetl
+++ b/examples/src/collections/ISized.jetl
@@ -1,3 +1,3 @@
-interface class ISized {
+virtual class ISized {
   val size : Int
 }
\ No newline at end of file
diff --git a/examples/src/collections/LinkedList.jetl b/examples/src/collections/LinkedList.jetl
index 43be0302cea..d1901a24fea 100644
--- a/examples/src/collections/LinkedList.jetl
+++ b/examples/src/collections/LinkedList.jetl
@@ -6,7 +6,7 @@ class LinkedList<T> : IMutableList<T> {
 
   private var head : Item = null
   private var tail : Item = null
-  override var size { get; private set; }
+  override var size  get private set;
 
   override fun add(index : Int, value : T) {
     size++
@@ -29,7 +29,7 @@ class LinkedList<T> : IMutableList<T> {
   }
 
   private fun checkIndex(index : Int) {
-    if (!index in [0..size-1]) {
+    if (index !in 0..size-1) {
       throw IndexOutOfBoundsException(index)
     }
   }
@@ -63,7 +63,7 @@ class LinkedList<T> : IMutableList<T> {
 
   private fun itemAt(index : Int) {
     var result = head
-    for (i in [1..index]) {
+    for (i in 1..index) {
       result = result.next
     }
     return result
diff --git a/examples/src/collections/List.jetl b/examples/src/collections/List.jetl
index 14cd75594d3..e7bee51ca45 100644
--- a/examples/src/collections/List.jetl
+++ b/examples/src/collections/List.jetl
@@ -3,13 +3,11 @@ enum class List<out T>(theSize : Int) : IList<T> {
 
   Cons<T>(val value : T, val tail : List<T>) : List<T>(1 + tail.size)
 
-  override val size : Int {
+  override val size : Int
     get() = theSize
-  }
 
-  override val isEmpty : Boolean {
+  override val isEmpty : Boolean
     get() = this == Nil
-  }
 
   override fun iterator() = new IIterator() {
     private var current = List.this
diff --git a/examples/src/io/IOSamples.jetl b/examples/src/io/IOSamples.jetl
index 8f0b10ce79f..c51b03a643f 100644
--- a/examples/src/io/IOSamples.jetl
+++ b/examples/src/io/IOSamples.jetl
@@ -1,8 +1,8 @@
-interface class IAdder<in T> {
+virtual class IAdder<in T> {
   fun add(item : T) : Boolean
 }
 
-interface class ICloseable {
+virtual class ICloseable {
   fun close()
 }
 
@@ -24,20 +24,19 @@ class FileInput : IIterator<Byte>, JavaCloseableWrapper {
   override fun next() {
     if (!nextUsed) {
       nextUsed = true
-      return next.as<Byte>
+      return next as Byte
     }
     return
   }
-  
-  override val hasNext {
+
+  override val hasNext
     get() { // implicitly throws IOException
       if (nextUsed && next != -1) {
         nextUsed = false
         next = stream.read() // throws IOException
       }
-      return next != -1        
+      return next != -1
     }
-  }
 }
 
 class FileOutput throws IOException : IAdder<Byte>, JavaCloseableWrapper {
diff --git a/examples/src/map/IMap.jetl b/examples/src/map/IMap.jetl
index 4f91bd5e996..0b912bb838d 100644
--- a/examples/src/map/IMap.jetl
+++ b/examples/src/map/IMap.jetl
@@ -1,4 +1,4 @@
-interface class IMap<in K, out V> {
+virtual class IMap<in K, out V> {
   
 
 }
\ No newline at end of file
diff --git a/examples/src/priorityqueues/BinaryHeap.jetl b/examples/src/priorityqueues/BinaryHeap.jetl
index 21188988a2e..1b46d2af79b 100644
--- a/examples/src/priorityqueues/BinaryHeap.jetl
+++ b/examples/src/priorityqueues/BinaryHeap.jetl
@@ -95,12 +95,11 @@ class BinaryHeap<T> : IPriorityQueue<T> {
 
 }
 
-extension fun IMutableList<T>.swap(a : Int, b : Int) {
+fun IMutableList<T>.swap(a : Int, b : Int) {
   val t = this[a]
   this[a] = this[b]
   this[b] = t
 }
 
-extension val IList<T>.lastIndex : Int
+val IList<T>.lastIndex : Int
   get() = this.size - 1
-
diff --git a/examples/src/priorityqueues/IPriorityQueue.jetl b/examples/src/priorityqueues/IPriorityQueue.jetl
index 01e5f357eaf..b343cd49cc3 100644
--- a/examples/src/priorityqueues/IPriorityQueue.jetl
+++ b/examples/src/priorityqueues/IPriorityQueue.jetl
@@ -1,4 +1,4 @@
-interface class IPriorityQueue<T> {
+virtual class IPriorityQueue<T> {
   fun extract() : T
   fun add(item : T)
   val isEmpty : Boolean
diff --git a/examples/src/priorityqueues/PriorityQueueAsPushPop.jetl b/examples/src/priorityqueues/PriorityQueueAsPushPop.jetl
index 0bbc006f7e1..2502a91b39f 100644
--- a/examples/src/priorityqueues/PriorityQueueAsPushPop.jetl
+++ b/examples/src/priorityqueues/PriorityQueueAsPushPop.jetl
@@ -1,7 +1,6 @@
 class PriorityQueueAsPushPop<T> wraps(wrapped : IPriorityQueue<T>) : IPushPop<T> {
   override fun pop() = wrapped.extract()
   override fun push(item : T) = wrapped.add(item)
-  override val isEmpty {
+  override val isEmpty 
     get() = wrapped.isEmpty
-  }
 }
\ No newline at end of file
diff --git a/examples/src/util/Comparison.jetl b/examples/src/util/Comparison.jetl
index 1af0c99ff2e..cd8935ff025 100644
--- a/examples/src/util/Comparison.jetl
+++ b/examples/src/util/Comparison.jetl
@@ -2,15 +2,15 @@ type Comparison<in T> = {(T, T) : Int}
 
 fun naturalOrder<in T : IComparable<T>>(a : T, b : T) : Int = a.compareTo(b)
 
-fun castingNaturalOrder(a : Object, b : Object) : Int = a.as<Comparable<Object>>.compareTo(b.as<Comparable<Object>>)
+fun castingNaturalOrder(a : Object, b : Object) : Int = (a as Comparable<Object>).compareTo(b as Comparable<Object>)
 
 enum class ComparisonResult {
-  LS,EQ, GR
+  LS, EQ, GR
 }
 
 type MatchableComparison<in T> = {(T, T) : ComparisonResult}
 
-fun asMatchableComparison<T>(cmp : Comparison<T>) : MatchableComparison<T> = {a, b =>
+fun asMatchableComparison<T>(cmp : Comparison<T>) : MatchableComparison<T> = {(a, b) =>
   val res = cmp(a, b)
   if (res == 0) return ComparisonResult.EQ
   if (res < 0) return ComparisonResult.LS
diff --git a/examples/src/util/IComparable.jetl b/examples/src/util/IComparable.jetl
index 79d19a364e6..b802c381464 100644
--- a/examples/src/util/IComparable.jetl
+++ b/examples/src/util/IComparable.jetl
@@ -1,3 +1,3 @@
-interface class IComparable<in T> {
+virtual class IComparable<in T> {
   fun compareTo(other : T) : Int
 }
\ No newline at end of file