From 50b341efe5e30ded9b65edf72a7a5de2d2f20e30 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Sun, 17 Nov 2019 16:14:24 -0800
Subject: [PATCH 01/59] -

---
 project/build.properties                 |  2 +-
 src/main/scala/IntersectionTypes.scala   |  2 +-
 src/main/scala/MultiversalEquality.scala | 18 +++++++++++-------
 3 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/project/build.properties b/project/build.properties
index c0bab04..6adcdc7 100644
--- a/project/build.properties
+++ b/project/build.properties
@@ -1 +1 @@
-sbt.version=1.2.8
+sbt.version=1.3.3
diff --git a/src/main/scala/IntersectionTypes.scala b/src/main/scala/IntersectionTypes.scala
index 9ebeed4..9f7d4e2 100644
--- a/src/main/scala/IntersectionTypes.scala
+++ b/src/main/scala/IntersectionTypes.scala
@@ -21,7 +21,7 @@ object IntersectionTypes {
   }
 
   def test: Unit = {
-
+    // Seems like these parameters should be of type P:
     def euclideanDistance(p1: X & Y, p2: X & Y) = {
       Math.sqrt(Math.pow(p2.y - p1.y, 2) + Math.pow(p2.x - p1.x, 2))
     }
diff --git a/src/main/scala/MultiversalEquality.scala b/src/main/scala/MultiversalEquality.scala
index 5152bd7..0846b1b 100644
--- a/src/main/scala/MultiversalEquality.scala
+++ b/src/main/scala/MultiversalEquality.scala
@@ -4,22 +4,23 @@ import scala.language.strictEquality
   * Multiversal Equality: https://dotty.epfl.ch/docs/reference/contextual/multiversal-equality.html
   * scala.Eq definition: https://github.com/lampepfl/dotty/blob/master/library/src/scala/Eql.scala
   */
-object MultiversalEquality {
+object MultiversalEquality extends App {
 
-  def test: Unit = {
+  def test(): Unit = {
 
     // Values of types Int and String cannot be compared with == or !=,
     // unless we add the derived delegate instance like:
     given Eql[Int, String] = Eql.derived
-    println(3 == "3")
+    println("3 == \"3\": " + (3 == "3"))
 
     // By default, all numbers are comparable, because of;
     // implicit def eqlNumber: Eql[Number, Number] = derived
-    println(3 == 5.1)
+    println("3 == 5.1: " + (3 == 5.1))
 
     // By default, all Sequences are comparable, because of;
     // implicit def eqlSeq[T, U](implicit eq: Eql[T, U]): Eql[GenSeq[T], GenSeq[U]] = derived
-    println(List(1, 2) == Vector(1, 2))
+    // This fails, why?
+    println("List(1, 2) == Vector(1, 2)): " + List(1, 2) == Vector(1, 2))
 
     class A(a: Int)
     class B(b: Int)
@@ -27,12 +28,15 @@ object MultiversalEquality {
     val a = new A(4)
     val b = new B(4)
 
+    // Two arrays in Scala 2 do not compare equal so why should this work?
+    println("Array(1, 2) == Array(1, 2): " + Array(1, 2) == Array(1, 2))
+
     // scala.language.strictEquality is enabled, therefore we need some extra delegate instances
     // to compare instances of A and B.
     given Eql[A, B] = Eql.derived
     given Eql[B, A] = Eql.derived
 
-    println(a != b)
-    println(b == a)
+    println("a != b: " + (a != b))
+    println("b == a: " + (b == a))
   }
 }

From 00f50150d3d8eb59d5547d1c883f0b233f3fccff Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Sun, 17 Nov 2019 16:28:06 -0800
Subject: [PATCH 02/59] -

---
 src/main/scala/MultiversalEquality.scala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/scala/MultiversalEquality.scala b/src/main/scala/MultiversalEquality.scala
index 0846b1b..73bf5b7 100644
--- a/src/main/scala/MultiversalEquality.scala
+++ b/src/main/scala/MultiversalEquality.scala
@@ -4,7 +4,7 @@ import scala.language.strictEquality
   * Multiversal Equality: https://dotty.epfl.ch/docs/reference/contextual/multiversal-equality.html
   * scala.Eq definition: https://github.com/lampepfl/dotty/blob/master/library/src/scala/Eql.scala
   */
-object MultiversalEquality extends App {
+  object MultiversalEquality extends App {
 
   def test(): Unit = {
 

From 6cf73f0c8277c88fa52377c6562b7c395d5b71ad Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Sun, 17 Nov 2019 16:29:08 -0800
Subject: [PATCH 03/59] -

---
 src/main/scala/MultiversalEquality.scala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/scala/MultiversalEquality.scala b/src/main/scala/MultiversalEquality.scala
index 73bf5b7..7a1f2c9 100644
--- a/src/main/scala/MultiversalEquality.scala
+++ b/src/main/scala/MultiversalEquality.scala
@@ -6,7 +6,7 @@ import scala.language.strictEquality
   */
   object MultiversalEquality extends App {
 
-  def test(): Unit = {
+  def test: Unit = {
 
     // Values of types Int and String cannot be compared with == or !=,
     // unless we add the derived delegate instance like:

From 08c5ddf442c2f4886563df135d4cf5e85ef78632 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Sun, 17 Nov 2019 16:39:25 -0800
Subject: [PATCH 04/59] -

---
 src/main/scala/MultiversalEquality.scala | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/main/scala/MultiversalEquality.scala b/src/main/scala/MultiversalEquality.scala
index 7a1f2c9..e73b37e 100644
--- a/src/main/scala/MultiversalEquality.scala
+++ b/src/main/scala/MultiversalEquality.scala
@@ -20,7 +20,7 @@ import scala.language.strictEquality
     // By default, all Sequences are comparable, because of;
     // implicit def eqlSeq[T, U](implicit eq: Eql[T, U]): Eql[GenSeq[T], GenSeq[U]] = derived
     // This fails, why?
-    println("List(1, 2) == Vector(1, 2)): " + List(1, 2) == Vector(1, 2))
+    println("List(1, 2) == Vector(1, 2)): " + (List(1, 2) == Vector(1, 2)))
 
     class A(a: Int)
     class B(b: Int)
@@ -29,7 +29,7 @@ import scala.language.strictEquality
     val b = new B(4)
 
     // Two arrays in Scala 2 do not compare equal so why should this work?
-    println("Array(1, 2) == Array(1, 2): " + Array(1, 2) == Array(1, 2))
+    //println("Array(1, 2) == Array(1, 2): " + (Array(1, 2) == Array(1, 2)))
 
     // scala.language.strictEquality is enabled, therefore we need some extra delegate instances
     // to compare instances of A and B.

From 5740b2ecf5d437922d0110645e778268b4086a35 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Sun, 17 Nov 2019 17:00:41 -0800
Subject: [PATCH 05/59] -

---
 src/main/scala/AutoParamTupling.scala    | 20 ++++++--------------
 src/main/scala/ContextQueries.scala      |  7 ++-----
 src/main/scala/Conversion.scala          |  6 +-----
 src/main/scala/EnumTypes.scala           | 12 ++++++------
 src/main/scala/ImpliedInstances.scala    | 23 +++++++++++------------
 src/main/scala/IntersectionTypes.scala   |  6 ++----
 src/main/scala/Main.scala                | 16 ----------------
 src/main/scala/MultiversalEquality.scala |  5 ++---
 src/main/scala/NamedTypeArguments.scala  |  9 ++-------
 src/main/scala/PatternMatching.scala     | 13 ++-----------
 src/main/scala/StructuralTypes.scala     |  6 ++----
 src/main/scala/TraitParams.scala         |  3 +--
 src/main/scala/TypeLambdas.scala         |  5 +----
 src/main/scala/UnionTypes.scala          |  5 +----
 14 files changed, 39 insertions(+), 97 deletions(-)

diff --git a/src/main/scala/AutoParamTupling.scala b/src/main/scala/AutoParamTupling.scala
index b72bab8..c7a1e76 100644
--- a/src/main/scala/AutoParamTupling.scala
+++ b/src/main/scala/AutoParamTupling.scala
@@ -1,24 +1,16 @@
-
 /**
   * Automatic Tupling of Function Params: https://dotty.epfl.ch/docs/reference/other-new-features/auto-parameter-tupling.html
   */
-object AutoParamTupling {
-
+object AutoParamTupling extends App {
   def test: Unit = {
-
-    /**
-      * In order to get thread safety, you need to put @volatile before lazy vals.
-      * https://dotty.epfl.ch/docs/reference/changed-features/lazy-vals.html
-      */
+    /** In order to get thread safety, you need to put @volatile before lazy vals.
+      * https://dotty.epfl.ch/docs/reference/changed-features/lazy-vals.html */
     @volatile lazy val xs: List[String] = List("d", "o", "t", "t", "y")
 
-    /**
-      * Current behaviour in Scala 2.12.2 :
+    /** Current behaviour in Scala 2.12.2 :
       * error: missing parameter type
       * Note: The expected type requires a one-argument function accepting a 2-Tuple.
-      * Consider a pattern matching anonymous function, `{ case (s, i) =>  ... }`
-      */
+      * Consider a pattern matching anonymous function, `{ case (s, i) =>  ... }` */
     xs.zipWithIndex.map((s, i) => println(s"$i: $s"))
-
   }
-}
\ No newline at end of file
+}
diff --git a/src/main/scala/ContextQueries.scala b/src/main/scala/ContextQueries.scala
index 52873b0..68d2e61 100644
--- a/src/main/scala/ContextQueries.scala
+++ b/src/main/scala/ContextQueries.scala
@@ -7,8 +7,7 @@ import scala.util.Try
   * - http://dotty.epfl.ch/docs/reference/contextual/query-types.html,
   * - https://www.scala-lang.org/blog/2016/12/07/implicit-function-types.html
   */
-object ContextQueries /* Formerly known as Implicit Function Types */ {
-
+object ContextQueries extends App /* Formerly known as Implicit Function Types */ {
   object context {
     // type alias Contextual
     type Contextual[T] = (given ExecutionContext) => T
@@ -20,7 +19,6 @@ object ContextQueries /* Formerly known as Implicit Function Types */ {
   }
 
   object parse {
-
     type Parseable[T] = (given ImpliedInstances.StringParser[T]) => Try[T]
 
     def sumStrings(x: String, y: String): Parseable[Int] = {
@@ -36,13 +34,12 @@ object ContextQueries /* Formerly known as Implicit Function Types */ {
   }
 
   def test: Unit = {
-
     import ExecutionContext.Implicits.global
+
     context.asyncSum(3, 4).foreach(println)
     context.asyncMult(3, 4).foreach(println)
 
     println(parse.sumStrings("3", "4"))
     println(parse.sumStrings("3", "a"))
   }
-
 }
diff --git a/src/main/scala/Conversion.scala b/src/main/scala/Conversion.scala
index 06b013e..ae6b3ee 100644
--- a/src/main/scala/Conversion.scala
+++ b/src/main/scala/Conversion.scala
@@ -3,8 +3,7 @@ import scala.language.implicitConversions
 /**
   *  Conversions: http://dotty.epfl.ch/docs/reference/contextual/conversions.html
   */
-object Conversion {
-
+object Conversion extends App {
   case class IntWrapper(a: Int) extends AnyVal
   case class DoubleWrapper(b: Double) extends AnyVal
 
@@ -31,7 +30,4 @@ object Conversion {
     println(useConversion)
     println(convert(new IntWrapper(42)))
   }
-
-
-
 }
diff --git a/src/main/scala/EnumTypes.scala b/src/main/scala/EnumTypes.scala
index 7996626..d3a4eef 100644
--- a/src/main/scala/EnumTypes.scala
+++ b/src/main/scala/EnumTypes.scala
@@ -1,8 +1,7 @@
 /**
   * Enum Types: http://dotty.epfl.ch/docs/reference/enums/adts.html
   */
-object EnumTypes {
-
+object EnumTypes extends App {
   enum ListEnum[+A] {
     case Cons(h: A, t: ListEnum[A])
     case Empty
@@ -10,7 +9,9 @@ object EnumTypes {
 
   enum Planet(mass: Double, radius: Double) {
     private final val G = 6.67300E-11
+
     def surfaceGravity = G * mass / (radius * radius)
+
     def surfaceWeight(otherMass: Double) =  otherMass * surfaceGravity
 
     case Mercury extends Planet(3.303e+23, 2.4397e6)
@@ -24,19 +25,18 @@ object EnumTypes {
   }
 
   def test: Unit = {
-
     val emptyList = ListEnum.Empty
     val list = ListEnum.Cons(1, ListEnum.Cons(2, ListEnum.Cons(3, ListEnum.Empty)))
     println(emptyList)
-    println(s"${list}\n")
+    println(s"$list\n")
 
-    def calculateEarthWeightOnPlanets(earthWeight: Double) = {
+    def calculateEarthWeightOnPlanets(earthWeight: Double): Unit = {
       val mass = earthWeight/Planet.Earth.surfaceGravity
       for (p <- Planet.values)
         println(s"Your weight on $p is ${p.surfaceWeight(mass)}")
+      ()
     }
 
     calculateEarthWeightOnPlanets(80)
   }
-
 }
diff --git a/src/main/scala/ImpliedInstances.scala b/src/main/scala/ImpliedInstances.scala
index e4f0433..5087892 100644
--- a/src/main/scala/ImpliedInstances.scala
+++ b/src/main/scala/ImpliedInstances.scala
@@ -4,36 +4,35 @@ import scala.util.{Success, Try}
   * Implied Instances:
   * - https://dotty.epfl.ch/docs/reference/contextual/instance-defs.html
   */
-object ImpliedInstances {
-
+object ImpliedInstances extends App {
   sealed trait StringParser[A] {
     def parse(s: String): Try[A]
   }
 
   object StringParser {
-
     def apply[A](given parser: StringParser[A]): StringParser[A] = parser
 
-    private def baseParser[A](f: String ⇒ Try[A]): StringParser[A] = new StringParser[A] {
-      override def parse(s: String): Try[A] = f(s)
-    }
+    private def baseParser[A](f: String ⇒ Try[A]): StringParser[A] =
+      new StringParser[A] {
+        override def parse(s: String): Try[A] = f(s)
+      }
 
     given stringParser: StringParser[String] = baseParser(Success(_))
     given intParser: StringParser[Int] = baseParser(s ⇒ Try(s.toInt))
 
-    given optionParser[A](given parser: => StringParser[A]): StringParser[Option[A]] = new StringParser[Option[A]] {
-      override def parse(s: String): Try[Option[A]] = s match {
-        case "" ⇒ Success(None) // implicit parser not used.
-        case str ⇒ parser.parse(str).map(x ⇒ Some(x)) // implicit parser is evaluated at here
+    given optionParser[A](given parser: => StringParser[A]): StringParser[Option[A]] =
+      new StringParser[Option[A]] {
+        override def parse(s: String): Try[Option[A]] = s match {
+          case "" ⇒ Success(None) // implicit parser not used.
+          case str ⇒ parser.parse(str).map(x ⇒ Some(x)) // implicit parser is evaluated at here
+        }
       }
-    }
   }
 
   def test: Unit = {
     println(implicitly[StringParser[Option[Int]]].parse("21"))
     println(implicitly[StringParser[Option[Int]]].parse(""))
     println(implicitly[StringParser[Option[Int]]].parse("21a"))
-
     println(implicitly[StringParser[Option[Int]]](StringParser.optionParser[Int]).parse("42"))
   }
 }
diff --git a/src/main/scala/IntersectionTypes.scala b/src/main/scala/IntersectionTypes.scala
index 9f7d4e2..cb4e200 100644
--- a/src/main/scala/IntersectionTypes.scala
+++ b/src/main/scala/IntersectionTypes.scala
@@ -2,7 +2,6 @@
   * Intersection Types: https://dotty.epfl.ch/docs/reference/new-types/intersection-types.html
   */
 object IntersectionTypes {
-
   sealed trait X {
     def x: Double
     def tpe: X
@@ -13,6 +12,7 @@ object IntersectionTypes {
     def tpe: Y
   }
 
+  // The compiler treats P and PP as equivalent and interchangeable types
   type P = Y & X
   type PP = X & Y
 
@@ -21,14 +21,12 @@ object IntersectionTypes {
   }
 
   def test: Unit = {
-    // Seems like these parameters should be of type P:
-    def euclideanDistance(p1: X & Y, p2: X & Y) = {
+    def euclideanDistance(p1: P, p2: P) = {
       Math.sqrt(Math.pow(p2.y - p1.y, 2) + Math.pow(p2.x - p1.x, 2))
     }
 
     val p1: P = Point(3, 4)
     val p2: PP = Point(6, 8)
     println(euclideanDistance(p1, p2))
-
   }
 }
diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index 18aed26..f3ba2a3 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -1,34 +1,19 @@
 
 object Main {
-
   def main(args: Array[String]): Unit = {
-
     runExample("Trait Params")(TraitParams.test)
-
     runExample("Enum Types")(EnumTypes.test)
-
     runExample("Context Queries")(ContextQueries.test)
-
     runExample("Implied Instances")(ImpliedInstances.test)
-
     runExample("Conversion")(Conversion.test)
-
     runExample("Union Types")(UnionTypes.test)
-
     runExample("Intersection Types")(IntersectionTypes.test)
-
     runExample("Type Lambda")(TypeLambdas.test)
-
     runExample("Multiversal Equality")(MultiversalEquality.test)
-
     runExample("Named Type Arguments")(NamedTypeArguments.test)
-
     runExample("Auto Param Tupling")(AutoParamTupling.test)
-
     runExample("Structural Types")(StructuralTypes.test)
-
     runExample("Pattern Matching")(PatternMatching.test)
-
   }
 
   private def runExample(name: String)(f: => Unit) = {
@@ -36,5 +21,4 @@ object Main {
     f
     println()
   }
-
 }
diff --git a/src/main/scala/MultiversalEquality.scala b/src/main/scala/MultiversalEquality.scala
index e73b37e..879838b 100644
--- a/src/main/scala/MultiversalEquality.scala
+++ b/src/main/scala/MultiversalEquality.scala
@@ -7,7 +7,6 @@ import scala.language.strictEquality
   object MultiversalEquality extends App {
 
   def test: Unit = {
-
     // Values of types Int and String cannot be compared with == or !=,
     // unless we add the derived delegate instance like:
     given Eql[Int, String] = Eql.derived
@@ -17,7 +16,7 @@ import scala.language.strictEquality
     // implicit def eqlNumber: Eql[Number, Number] = derived
     println("3 == 5.1: " + (3 == 5.1))
 
-    // By default, all Sequences are comparable, because of;
+    // By default, all Sequences are comparable (except Array), because of;
     // implicit def eqlSeq[T, U](implicit eq: Eql[T, U]): Eql[GenSeq[T], GenSeq[U]] = derived
     // This fails, why?
     println("List(1, 2) == Vector(1, 2)): " + (List(1, 2) == Vector(1, 2)))
@@ -28,7 +27,7 @@ import scala.language.strictEquality
     val a = new A(4)
     val b = new B(4)
 
-    // Two arrays in Scala 2 do not compare equal so why should this work?
+    // Two arrays in Scala do not compare equal so this is illegal code that must not compile?
     //println("Array(1, 2) == Array(1, 2): " + (Array(1, 2) == Array(1, 2)))
 
     // scala.language.strictEquality is enabled, therefore we need some extra delegate instances
diff --git a/src/main/scala/NamedTypeArguments.scala b/src/main/scala/NamedTypeArguments.scala
index 85cee9a..12a41f6 100644
--- a/src/main/scala/NamedTypeArguments.scala
+++ b/src/main/scala/NamedTypeArguments.scala
@@ -1,9 +1,7 @@
-
 /**
   * Named Type Arguments: https://dotty.epfl.ch/docs/reference/other-new-features/named-typeargs.html
   */
-object NamedTypeArguments {
-
+object NamedTypeArguments extends App {
   trait Functor[F[_]] {
     def map[A, B](fa: F[A])(f: A => B): F[B]
   }
@@ -13,7 +11,6 @@ object NamedTypeArguments {
   }
 
   def test: Unit = {
-
     def fmap[F[_], A, B](fa: F[A])(f: A => B)(implicit F: Functor[F]): F[B] = F.map(fa)(f)
 
     val result: List[Int] = fmap[F = List, A = Int, B = Int](List(1,2,3))(i => i + 1)
@@ -25,7 +22,5 @@ object NamedTypeArguments {
     val compile: List[String] = fmap[F = List, B = String](List(1,2,3))(i => (i + 1).toString)
 
     println(compile)
-
   }
-
-}
\ No newline at end of file
+}
diff --git a/src/main/scala/PatternMatching.scala b/src/main/scala/PatternMatching.scala
index 8e64e87..3193772 100644
--- a/src/main/scala/PatternMatching.scala
+++ b/src/main/scala/PatternMatching.scala
@@ -2,18 +2,14 @@
 /**
   * Pattern Matching: https://dotty.epfl.ch/docs/reference/changed-features/pattern-matching.html
   */
-object PatternMatching {
-
+object PatternMatching extends App {
   object booleanPattern {
-
     object Even {
       def unapply(s: String): Boolean = s.length % 2 == 0
     }
-
   }
 
   object productPattern {
-
     class Person(name: String, age: Int) extends Product {
       // if we not define that, it will give compile error.
       // we change the order
@@ -29,11 +25,9 @@ object PatternMatching {
     object Person {
       def unapply(a: (String, Int)): Person = new Person(a._1, a._2)
     }
-
   }
 
   object seqPattern {
-
     // adapted from http://danielwestheide.com/blog/2012/11/28/the-neophytes-guide-to-scala-part-2-extracting-sequences.html
     object Names {
       def unapplySeq(name: String): Option[Seq[String]] = {
@@ -46,7 +40,6 @@ object PatternMatching {
   }
 
   object namePattern {
-
     class Name(val name: String) {
       def get: String = name
       def isEmpty = name.isEmpty
@@ -59,7 +52,6 @@ object PatternMatching {
   }
 
   def test: Unit = {
-
     import booleanPattern._
 
     "even" match {
@@ -98,6 +90,5 @@ object PatternMatching {
       case Name(n) => println(s"name is $n")
       case _ => println("empty name")
     }
-
   }
-}
\ No newline at end of file
+}
diff --git a/src/main/scala/StructuralTypes.scala b/src/main/scala/StructuralTypes.scala
index 4eb60a4..2994d81 100644
--- a/src/main/scala/StructuralTypes.scala
+++ b/src/main/scala/StructuralTypes.scala
@@ -2,8 +2,7 @@
 /**
   * Structural Types: https://dotty.epfl.ch/docs/reference/changed-features/structural-types.html
   */
-object StructuralTypes {
-
+object StructuralTypes extends App {
   case class Record(elems: (String, Any)*) extends Selectable {
     def selectDynamic(name: String): Any = elems.find(_._1 == name).get._2
   }
@@ -20,9 +19,8 @@ object StructuralTypes {
   def test: Unit = {
     println(person.name)
     println(person.age)
-
     println(invalidPerson.name)
     // age field is java.util.NoSuchElementException: None.get
     //println(invalidPerson.age)
   }
-}
\ No newline at end of file
+}
diff --git a/src/main/scala/TraitParams.scala b/src/main/scala/TraitParams.scala
index 5d44099..a171226 100644
--- a/src/main/scala/TraitParams.scala
+++ b/src/main/scala/TraitParams.scala
@@ -1,7 +1,7 @@
 /**
   * Trait Parameters: https://dotty.epfl.ch/docs/reference/other-new-features/trait-parameters.html
   */
-object TraitParams {
+object TraitParams extends App {
 
   trait Base(val msg: String)
   class A extends Base("Hello")
@@ -11,7 +11,6 @@ object TraitParams {
   private def printMessages(msgs: (A | B)*) = println(msgs.map(_.msg).mkString(" "))
 
   def test: Unit = {
-
     printMessages(new A, new B)
 
     // Sanity check the classpath: this won't run if the dotty jar is not present.
diff --git a/src/main/scala/TypeLambdas.scala b/src/main/scala/TypeLambdas.scala
index bcbb5b8..555977e 100644
--- a/src/main/scala/TypeLambdas.scala
+++ b/src/main/scala/TypeLambdas.scala
@@ -1,19 +1,16 @@
 /**
   * Type Lambdas: https://dotty.epfl.ch/docs/reference/new-types/type-lambdas.html
   */
-object TypeLambdas {
-
+object TypeLambdas extends App {
   type T[+X, Y] = Map[Y, X]
 
   type Tuple = [X] =>> (X, X)
 
   def test: Unit = {
-
     val m: T[String, Int] = Map(1 -> "1")
     println(m)
 
     val tuple: Tuple[String] = ("a", "b")
     println(tuple)
   }
-
 }
diff --git a/src/main/scala/UnionTypes.scala b/src/main/scala/UnionTypes.scala
index ab3e365..472b8e1 100644
--- a/src/main/scala/UnionTypes.scala
+++ b/src/main/scala/UnionTypes.scala
@@ -1,8 +1,7 @@
 /**
   * Union Types: https://dotty.epfl.ch/docs/reference/new-types/union-types.html
   */
-object UnionTypes {
-
+object UnionTypes extends App {
   sealed trait Division
   final case class DivisionByZero(msg: String) extends Division
   final case class Success(double: Double) extends Division
@@ -24,7 +23,6 @@ object UnionTypes {
   }
 
   def test: Unit = {
-
     val divisionResultSuccess: DivisionResult = safeDivide(4, 2)
 
     // commutative
@@ -40,6 +38,5 @@ object UnionTypes {
     val emptyList: Empty | Cons[Any] = Empty()
     println(list)
     println(emptyList)
-
   }
 }

From 75418192ed1c82470f08339b0fe07dd8848c3a1d Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Sun, 17 Nov 2019 17:01:16 -0800
Subject: [PATCH 06/59] -

---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 3e6c916..95261e6 100644
--- a/README.md
+++ b/README.md
@@ -32,7 +32,7 @@ addSbtPlugin("ch.epfl.lamp" % "sbt-dotty" % "0.3.4")
 
 ### project/build.properties
 ```scala
-sbt.version=1.2.8
+sbt.version=1.3.3
 ```
 
 Older versions of sbt are not supported.

From 9e331c51284083d624124a233944fa3c530a8de1 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Sun, 17 Nov 2019 17:09:07 -0800
Subject: [PATCH 07/59] -

---
 src/main/scala/UnionTypes.scala | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/main/scala/UnionTypes.scala b/src/main/scala/UnionTypes.scala
index 472b8e1..5472fb7 100644
--- a/src/main/scala/UnionTypes.scala
+++ b/src/main/scala/UnionTypes.scala
@@ -10,7 +10,7 @@ object UnionTypes extends App {
   type DivisionResult = DivisionByZero | Success
 
   sealed trait List[+A]
-  final case class Empty() extends List[Nothing]
+  final class Empty extends List[Nothing]
   final case class Cons[+A](h: A, t: List[A]) extends List[A]
 
   private def safeDivide(a: Double, b: Double): DivisionResult = {
@@ -25,13 +25,13 @@ object UnionTypes extends App {
   def test: Unit = {
     val divisionResultSuccess: DivisionResult = safeDivide(4, 2)
 
-    // commutative
+    // Commutative
     val divisionResultFailure: Success | DivisionByZero = safeDivide(4, 0)
 
-    // calling `either` function with union typed value.
+    // Calling `either` function with union typed value.
     println(either(divisionResultSuccess))
 
-    // calling `either` function with union typed value.
+    // Calling `either` function with union typed value.
     println(either(divisionResultFailure))
 
     val list: Cons[Int] | Empty = Cons(1, Cons(2, Cons(3, Empty())))

From 41f40a30ec099c6ad8ceea188de663550edb449a Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Sun, 17 Nov 2019 17:32:34 -0800
Subject: [PATCH 08/59] -

---
 src/main/scala/ContextQueries.scala     | 11 +++++------
 src/main/scala/Conversion.scala         | 14 +++++++-------
 src/main/scala/EnumTypes.scala          |  4 +---
 src/main/scala/ImpliedInstances.scala   | 17 ++++++++---------
 src/main/scala/Main.scala               |  1 -
 src/main/scala/NamedTypeArguments.scala | 14 ++++++++------
 src/main/scala/PatternMatching.scala    |  6 +-----
 7 files changed, 30 insertions(+), 37 deletions(-)

diff --git a/src/main/scala/ContextQueries.scala b/src/main/scala/ContextQueries.scala
index 68d2e61..a8c810e 100644
--- a/src/main/scala/ContextQueries.scala
+++ b/src/main/scala/ContextQueries.scala
@@ -2,12 +2,10 @@
 import scala.concurrent.{ExecutionContext, Future}
 import scala.util.Try
 
-/**
-  * Context Queries:
+/** Context Queries (Formerly known as Implicit Function Types):
   * - http://dotty.epfl.ch/docs/reference/contextual/query-types.html,
-  * - https://www.scala-lang.org/blog/2016/12/07/implicit-function-types.html
-  */
-object ContextQueries extends App /* Formerly known as Implicit Function Types */ {
+  * - https://www.scala-lang.org/blog/2016/12/07/implicit-function-types.html */
+object ContextQueries extends App {
   object context {
     // type alias Contextual
     type Contextual[T] = (given ExecutionContext) => T
@@ -15,7 +13,8 @@ object ContextQueries extends App /* Formerly known as Implicit Function Types *
     // sum is expanded to sum(x, y)(ctx)
     def asyncSum(x: Int, y: Int): Contextual[Future[Int]] = Future(x + y)
 
-    def asyncMult(x: Int, y: Int)(given ctx: ExecutionContext) = Future(x * y)
+    def asyncMult(x: Int, y: Int)
+                 (given ctx: ExecutionContext) = Future(x * y)
   }
 
   object parse {
diff --git a/src/main/scala/Conversion.scala b/src/main/scala/Conversion.scala
index ae6b3ee..a60de3c 100644
--- a/src/main/scala/Conversion.scala
+++ b/src/main/scala/Conversion.scala
@@ -1,17 +1,17 @@
 import scala.language.implicitConversions
 
-/**
-  *  Conversions: http://dotty.epfl.ch/docs/reference/contextual/conversions.html
-  */
+/** Conversions: http://dotty.epfl.ch/docs/reference/contextual/conversions.html */
 object Conversion extends App {
   case class IntWrapper(a: Int) extends AnyVal
   case class DoubleWrapper(b: Double) extends AnyVal
 
-  def convert[T, U](x: T)(given converter: Conversion[T, U]): U = converter(x)
+  def convert[T, U](t: T)
+                   (given converter: Conversion[T, U]): U = converter(t)
 
-  given IntWrapperToDoubleWrapper: Conversion[IntWrapper, DoubleWrapper] = new Conversion[IntWrapper, DoubleWrapper] {
-    override def apply(i: IntWrapper): DoubleWrapper = new DoubleWrapper(i.a.toDouble)
-  }
+  given IntWrapperToDoubleWrapper: Conversion[IntWrapper, DoubleWrapper] =
+    new Conversion[IntWrapper, DoubleWrapper] {
+      override def apply(i: IntWrapper): DoubleWrapper = new DoubleWrapper(i.a.toDouble)
+    }
 
   def useConversion(given f: Conversion[IntWrapper, DoubleWrapper]) = {
     val y: IntWrapper = new IntWrapper(4)
diff --git a/src/main/scala/EnumTypes.scala b/src/main/scala/EnumTypes.scala
index d3a4eef..f6c567f 100644
--- a/src/main/scala/EnumTypes.scala
+++ b/src/main/scala/EnumTypes.scala
@@ -1,6 +1,4 @@
-/**
-  * Enum Types: http://dotty.epfl.ch/docs/reference/enums/adts.html
-  */
+/** Enum Types: http://dotty.epfl.ch/docs/reference/enums/adts.html */
 object EnumTypes extends App {
   enum ListEnum[+A] {
     case Cons(h: A, t: ListEnum[A])
diff --git a/src/main/scala/ImpliedInstances.scala b/src/main/scala/ImpliedInstances.scala
index 5087892..700682a 100644
--- a/src/main/scala/ImpliedInstances.scala
+++ b/src/main/scala/ImpliedInstances.scala
@@ -1,9 +1,7 @@
 import scala.util.{Success, Try}
 
-/**
-  * Implied Instances:
-  * - https://dotty.epfl.ch/docs/reference/contextual/instance-defs.html
-  */
+/** Implied Instances:
+  * - https://dotty.epfl.ch/docs/reference/contextual/instance-defs.html */
 object ImpliedInstances extends App {
   sealed trait StringParser[A] {
     def parse(s: String): Try[A]
@@ -24,15 +22,16 @@ object ImpliedInstances extends App {
       new StringParser[Option[A]] {
         override def parse(s: String): Try[Option[A]] = s match {
           case "" ⇒ Success(None) // implicit parser not used.
-          case str ⇒ parser.parse(str).map(x ⇒ Some(x)) // implicit parser is evaluated at here
+          case str ⇒ parser.parse(str).map(Some(_)) // implicit parser is evaluated here
         }
       }
   }
 
   def test: Unit = {
-    println(implicitly[StringParser[Option[Int]]].parse("21"))
-    println(implicitly[StringParser[Option[Int]]].parse(""))
-    println(implicitly[StringParser[Option[Int]]].parse("21a"))
-    println(implicitly[StringParser[Option[Int]]](StringParser.optionParser[Int]).parse("42"))
+    val spoi = implicitly[StringParser[Option[Int]]]
+    println(spoi.parse("21"))
+    println(spoi.parse(""))
+    println(spoi.parse("21a"))
+    println(StringParser.optionParser[Int].parse("42"))
   }
 }
diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index f3ba2a3..01107c0 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -1,4 +1,3 @@
-
 object Main {
   def main(args: Array[String]): Unit = {
     runExample("Trait Params")(TraitParams.test)
diff --git a/src/main/scala/NamedTypeArguments.scala b/src/main/scala/NamedTypeArguments.scala
index 12a41f6..a2ecb5d 100644
--- a/src/main/scala/NamedTypeArguments.scala
+++ b/src/main/scala/NamedTypeArguments.scala
@@ -1,17 +1,19 @@
-/**
-  * Named Type Arguments: https://dotty.epfl.ch/docs/reference/other-new-features/named-typeargs.html
-  */
+/** Named Type Arguments: https://dotty.epfl.ch/docs/reference/other-new-features/named-typeargs.html */
 object NamedTypeArguments extends App {
   trait Functor[F[_]] {
-    def map[A, B](fa: F[A])(f: A => B): F[B]
+    def map[A, B](fa: F[A])
+                 (f: A => B): F[B]
   }
 
   implicit object listFunctor extends Functor[List] {
-    override def map[A, B](fa: List[A])(f: A => B): List[B] = fa.map(f)
+    override def map[A, B](fa: List[A])
+                          (f: A => B): List[B] = fa.map(f)
   }
 
   def test: Unit = {
-    def fmap[F[_], A, B](fa: F[A])(f: A => B)(implicit F: Functor[F]): F[B] = F.map(fa)(f)
+    def fmap[F[_], A, B](fa: F[A])
+                        (f: A => B)
+                        (implicit F: Functor[F]): F[B] = F.map(fa)(f)
 
     val result: List[Int] = fmap[F = List, A = Int, B = Int](List(1,2,3))(i => i + 1)
 
diff --git a/src/main/scala/PatternMatching.scala b/src/main/scala/PatternMatching.scala
index 3193772..14b77c8 100644
--- a/src/main/scala/PatternMatching.scala
+++ b/src/main/scala/PatternMatching.scala
@@ -1,7 +1,4 @@
-
-/**
-  * Pattern Matching: https://dotty.epfl.ch/docs/reference/changed-features/pattern-matching.html
-  */
+/** Pattern Matching: https://dotty.epfl.ch/docs/reference/changed-features/pattern-matching.html */
 object PatternMatching extends App {
   object booleanPattern {
     object Even {
@@ -48,7 +45,6 @@ object PatternMatching extends App {
     object Name {
       def unapply(s: String): Name = new Name(s)
     }
-
   }
 
   def test: Unit = {

From 0bb2a9cc315fee71b20cba2206c054c5de4442f8 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Sun, 17 Nov 2019 17:35:41 -0800
Subject: [PATCH 09/59] -

---
 src/main/scala/StructuralTypes.scala | 5 +----
 src/main/scala/TraitParams.scala     | 9 ++++-----
 src/main/scala/TypeLambdas.scala     | 4 +---
 src/main/scala/UnionTypes.scala      | 4 +---
 4 files changed, 7 insertions(+), 15 deletions(-)

diff --git a/src/main/scala/StructuralTypes.scala b/src/main/scala/StructuralTypes.scala
index 2994d81..06223d9 100644
--- a/src/main/scala/StructuralTypes.scala
+++ b/src/main/scala/StructuralTypes.scala
@@ -1,7 +1,4 @@
-
-/**
-  * Structural Types: https://dotty.epfl.ch/docs/reference/changed-features/structural-types.html
-  */
+/** Structural Types: https://dotty.epfl.ch/docs/reference/changed-features/structural-types.html */
 object StructuralTypes extends App {
   case class Record(elems: (String, Any)*) extends Selectable {
     def selectDynamic(name: String): Any = elems.find(_._1 == name).get._2
diff --git a/src/main/scala/TraitParams.scala b/src/main/scala/TraitParams.scala
index a171226..0e81fa8 100644
--- a/src/main/scala/TraitParams.scala
+++ b/src/main/scala/TraitParams.scala
@@ -1,8 +1,5 @@
-/**
-  * Trait Parameters: https://dotty.epfl.ch/docs/reference/other-new-features/trait-parameters.html
-  */
+/** Trait Parameters: https://dotty.epfl.ch/docs/reference/other-new-features/trait-parameters.html */
 object TraitParams extends App {
-
   trait Base(val msg: String)
   class A extends Base("Hello")
   class B extends Base("Dotty!")
@@ -14,7 +11,9 @@ object TraitParams extends App {
     printMessages(new A, new B)
 
     // Sanity check the classpath: this won't run if the dotty jar is not present.
-    val x: Int => Int = z => z
+    val x: Int => Int =
+      z => z
+
     x(1)
   }
 }
diff --git a/src/main/scala/TypeLambdas.scala b/src/main/scala/TypeLambdas.scala
index 555977e..be1caa9 100644
--- a/src/main/scala/TypeLambdas.scala
+++ b/src/main/scala/TypeLambdas.scala
@@ -1,6 +1,4 @@
-/**
-  * Type Lambdas: https://dotty.epfl.ch/docs/reference/new-types/type-lambdas.html
-  */
+/** Type Lambdas: https://dotty.epfl.ch/docs/reference/new-types/type-lambdas.html */
 object TypeLambdas extends App {
   type T[+X, Y] = Map[Y, X]
 
diff --git a/src/main/scala/UnionTypes.scala b/src/main/scala/UnionTypes.scala
index 5472fb7..91146c2 100644
--- a/src/main/scala/UnionTypes.scala
+++ b/src/main/scala/UnionTypes.scala
@@ -1,6 +1,4 @@
-/**
-  * Union Types: https://dotty.epfl.ch/docs/reference/new-types/union-types.html
-  */
+/** Union Types: https://dotty.epfl.ch/docs/reference/new-types/union-types.html */
 object UnionTypes extends App {
   sealed trait Division
   final case class DivisionByZero(msg: String) extends Division

From 64fb2d428f201796566f76a72fa55c0a7c07003c Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 19 Nov 2019 10:28:59 -0800
Subject: [PATCH 10/59] -

---
 src/main/scala/Main.scala        |  1 +
 src/main/scala/Typeclasses.scala | 21 +++++++++++++++++++++
 2 files changed, 22 insertions(+)
 create mode 100644 src/main/scala/Typeclasses.scala

diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index 01107c0..0398dd7 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -1,5 +1,6 @@
 object Main {
   def main(args: Array[String]): Unit = {
+    runExample("Typeclasses")(Typeclasses.test)
     runExample("Trait Params")(TraitParams.test)
     runExample("Enum Types")(EnumTypes.test)
     runExample("Context Queries")(ContextQueries.test)
diff --git a/src/main/scala/Typeclasses.scala b/src/main/scala/Typeclasses.scala
new file mode 100644
index 0000000..38bc917
--- /dev/null
+++ b/src/main/scala/Typeclasses.scala
@@ -0,0 +1,21 @@
+/**
+  * Automatic Tupling of Function Params: https://dotty.epfl.ch/docs/reference/other-new-features/auto-parameter-tupling.html
+  */
+object Typeclasses extends App {
+  trait SemiGroup[T] {
+    def (x: T) combine (y: T): T
+  }
+
+  trait Monoid [T] extends SemiGroup[T] {
+    def unit: T
+  }
+
+  given Monoid[String] {
+    def (x: String) combine (y: String) = x.concat(y)
+    def unit = ""
+
+  def sum[T: Monoid](xs: List[T]): T =
+    xs.foldLeft(summon[Monoid[T]].unit)(_.combine(_))
+
+  def test: Unit = println("""sum("a", "b", "c"): """ + sum(List("a", "b", "c"))
+}

From 8514a350a6544ae2a9710c346c2f261f3e6bd219 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 19 Nov 2019 10:29:15 -0800
Subject: [PATCH 11/59] -

---
 src/main/scala/Typeclasses.scala | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/src/main/scala/Typeclasses.scala b/src/main/scala/Typeclasses.scala
index 38bc917..17bb3f5 100644
--- a/src/main/scala/Typeclasses.scala
+++ b/src/main/scala/Typeclasses.scala
@@ -1,6 +1,3 @@
-/**
-  * Automatic Tupling of Function Params: https://dotty.epfl.ch/docs/reference/other-new-features/auto-parameter-tupling.html
-  */
 object Typeclasses extends App {
   trait SemiGroup[T] {
     def (x: T) combine (y: T): T

From d6df577d6d3d014b0c05934895c2a9e75a0c1279 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 19 Nov 2019 10:31:35 -0800
Subject: [PATCH 12/59] -

---
 src/main/scala/Typeclasses.scala | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/main/scala/Typeclasses.scala b/src/main/scala/Typeclasses.scala
index 17bb3f5..d4f9143 100644
--- a/src/main/scala/Typeclasses.scala
+++ b/src/main/scala/Typeclasses.scala
@@ -10,9 +10,10 @@ object Typeclasses extends App {
   given Monoid[String] {
     def (x: String) combine (y: String) = x.concat(y)
     def unit = ""
+  }
 
   def sum[T: Monoid](xs: List[T]): T =
     xs.foldLeft(summon[Monoid[T]].unit)(_.combine(_))
 
-  def test: Unit = println("""sum("a", "b", "c"): """ + sum(List("a", "b", "c"))
+  def test: Unit = println("""sum("a", "b", "c"): """ + sum(List("a", "b", "c")))
 }

From b91bb4f552c28d8042418d7f6adeab5564f7b4af Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 19 Nov 2019 10:39:36 -0800
Subject: [PATCH 13/59] -

---
 build.sbt                        | 16 +++++++---------
 src/main/scala/Typeclasses.scala |  5 ++++-
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/build.sbt b/build.sbt
index 88e1cb0..9140e8e 100644
--- a/build.sbt
+++ b/build.sbt
@@ -1,9 +1,7 @@
-lazy val root = project
-  .in(file("."))
-  .settings(
-    name := "dotty-example-project",
-    description := "Example sbt project that compiles using Dotty",
-    version := "0.1.0",
-
-    scalaVersion := "0.20.0-RC1"
-  )
+description := "Example sbt project that compiles using Dotty"
+logBuffered in Test := false
+logLevel := Level.Warn
+logLevel in test := Level.Info
+name := "dotty-example-project"
+scalaVersion := "0.20.0-RC1"
+version := "0.1.0"
diff --git a/src/main/scala/Typeclasses.scala b/src/main/scala/Typeclasses.scala
index d4f9143..936063a 100644
--- a/src/main/scala/Typeclasses.scala
+++ b/src/main/scala/Typeclasses.scala
@@ -15,5 +15,8 @@ object Typeclasses extends App {
   def sum[T: Monoid](xs: List[T]): T =
     xs.foldLeft(summon[Monoid[T]].unit)(_.combine(_))
 
-  def test: Unit = println("""sum("a", "b", "c"): """ + sum(List("a", "b", "c")))
+  def test: Unit = {
+    println("\n\nasdf\nasdf\n\n")
+    println("""sum("a", "b", "c"): """ + sum(List("a", "b", "c")))
+  }
 }

From b8666eeab2f188b9bdccc5e3a0b32380aba688a2 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 19 Nov 2019 12:10:09 -0800
Subject: [PATCH 14/59] -

---
 src/main/scala/Typeclasses.scala | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/main/scala/Typeclasses.scala b/src/main/scala/Typeclasses.scala
index 936063a..4a50403 100644
--- a/src/main/scala/Typeclasses.scala
+++ b/src/main/scala/Typeclasses.scala
@@ -16,7 +16,6 @@ object Typeclasses extends App {
     xs.foldLeft(summon[Monoid[T]].unit)(_.combine(_))
 
   def test: Unit = {
-    println("\n\nasdf\nasdf\n\n")
     println("""sum("a", "b", "c"): """ + sum(List("a", "b", "c")))
   }
 }

From 281733d56a842cf78377b98b4316fe016b3b09e6 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 19 Nov 2019 13:40:05 -0800
Subject: [PATCH 15/59] -

---
 README.md                        | 8 ++++++++
 src/main/scala/Main.scala        | 3 ++-
 src/main/scala/Typeclasses.scala | 2 +-
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 95261e6..db407cb 100644
--- a/README.md
+++ b/README.md
@@ -7,6 +7,14 @@
 This is a normal sbt project, you can compile code with `sbt compile` and run it
 with `sbt run`, `sbt console` will start a Dotty REPL.
 
+You can run just one example from the `sbt console`, for example we can run `Typeclasses.test`:
+
+```
+$ sbt console
+scala> Typeclasses.test
+sum("a", "b", "c"): abc
+```
+
 If compiling this example project fails, you probably have a global sbt plugin
 that does not work with dotty, try to disable all plugins in
 `~/.sbt/1.0/plugins` and `~/.sbt/1.0`.
diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index 0398dd7..30632e6 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -16,7 +16,8 @@ object Main {
     runExample("Pattern Matching")(PatternMatching.test)
   }
 
-  private def runExample(name: String)(f: => Unit) = {
+  private def runExample(name: String)
+                        (f: => Unit) = {
     println(Console.MAGENTA + s"$name example:" + Console.RESET)
     f
     println()
diff --git a/src/main/scala/Typeclasses.scala b/src/main/scala/Typeclasses.scala
index 4a50403..0d6f1b8 100644
--- a/src/main/scala/Typeclasses.scala
+++ b/src/main/scala/Typeclasses.scala
@@ -1,4 +1,4 @@
-object Typeclasses extends App {
+object Typeclasses {
   trait SemiGroup[T] {
     def (x: T) combine (y: T): T
   }

From 6aeb463ee6702b06f936d77358387c5a0105dff6 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Sun, 24 Nov 2019 07:13:02 -0800
Subject: [PATCH 16/59] Update build.properties

---
 project/build.properties | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/project/build.properties b/project/build.properties
index 6adcdc7..5a9ed92 100644
--- a/project/build.properties
+++ b/project/build.properties
@@ -1 +1 @@
-sbt.version=1.3.3
+sbt.version=1.3.4

From 36457bad27e6e4a1cddd0f65ae5a059fd8d3ea99 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Mon, 25 Nov 2019 11:25:10 -0500
Subject: [PATCH 17/59] -

---
 README.md                        |  4 ++--
 src/main/scala/Typeclasses.scala | 13 ++++---------
 2 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/README.md b/README.md
index db407cb..a336d89 100644
--- a/README.md
+++ b/README.md
@@ -40,10 +40,10 @@ addSbtPlugin("ch.epfl.lamp" % "sbt-dotty" % "0.3.4")
 
 ### project/build.properties
 ```scala
-sbt.version=1.3.3
+sbt.version=1.3.4
 ```
 
-Older versions of sbt are not supported.
+Versions of sbt older than 1.3.3 are not supported.
 
 
 ### build.sbt
diff --git a/src/main/scala/Typeclasses.scala b/src/main/scala/Typeclasses.scala
index 0d6f1b8..40751b5 100644
--- a/src/main/scala/Typeclasses.scala
+++ b/src/main/scala/Typeclasses.scala
@@ -1,21 +1,16 @@
 object Typeclasses {
-  trait SemiGroup[T] {
+  trait SemiGroup[T] with
     def (x: T) combine (y: T): T
-  }
 
-  trait Monoid [T] extends SemiGroup[T] {
+  trait Monoid [T] extends SemiGroup[T] with
     def unit: T
-  }
 
-  given Monoid[String] {
+  given Monoid[String] with
     def (x: String) combine (y: String) = x.concat(y)
     def unit = ""
-  }
 
   def sum[T: Monoid](xs: List[T]): T =
     xs.foldLeft(summon[Monoid[T]].unit)(_.combine(_))
 
-  def test: Unit = {
-    println("""sum("a", "b", "c"): """ + sum(List("a", "b", "c")))
-  }
+  def test: Unit = println("""sum("a", "b", "c"): """ + sum(List("a", "b", "c")))
 }

From 142d08b710893aa5a62abc134e843af0660d8cd1 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Mon, 25 Nov 2019 11:37:03 -0500
Subject: [PATCH 18/59] -

---
 src/main/scala/IntersectionTypes.scala | 2 +-
 src/main/scala/TraitParams.scala       | 2 +-
 src/main/scala/Typeclasses.scala       | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/main/scala/IntersectionTypes.scala b/src/main/scala/IntersectionTypes.scala
index cb4e200..ea80de3 100644
--- a/src/main/scala/IntersectionTypes.scala
+++ b/src/main/scala/IntersectionTypes.scala
@@ -1,7 +1,7 @@
 /**
   * Intersection Types: https://dotty.epfl.ch/docs/reference/new-types/intersection-types.html
   */
-object IntersectionTypes {
+object IntersectionTypes extends App {
   sealed trait X {
     def x: Double
     def tpe: X
diff --git a/src/main/scala/TraitParams.scala b/src/main/scala/TraitParams.scala
index 0e81fa8..c750bd7 100644
--- a/src/main/scala/TraitParams.scala
+++ b/src/main/scala/TraitParams.scala
@@ -5,7 +5,7 @@ object TraitParams extends App {
   class B extends Base("Dotty!")
 
   // Union types only exist in Dotty, so there's no chance that this will accidentally be compiled with Scala 2
-  private def printMessages(msgs: (A | B)*) = println(msgs.map(_.msg).mkString(" "))
+  private def printMessages(msgs: (A | B)*): Unit = println(msgs.map(_.msg).mkString(" "))
 
   def test: Unit = {
     printMessages(new A, new B)
diff --git a/src/main/scala/Typeclasses.scala b/src/main/scala/Typeclasses.scala
index 40751b5..92d6035 100644
--- a/src/main/scala/Typeclasses.scala
+++ b/src/main/scala/Typeclasses.scala
@@ -1,4 +1,4 @@
-object Typeclasses {
+object Typeclasses extends App {
   trait SemiGroup[T] with
     def (x: T) combine (y: T): T
 

From 163776adb1eac05493e3be40bb7efb40af17b540 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Mon, 25 Nov 2019 11:48:28 -0500
Subject: [PATCH 19/59] -

---
 src/main/scala/ExtensionClasses.scala | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
 create mode 100644 src/main/scala/ExtensionClasses.scala

diff --git a/src/main/scala/ExtensionClasses.scala b/src/main/scala/ExtensionClasses.scala
new file mode 100644
index 0000000..3ec3e75
--- /dev/null
+++ b/src/main/scala/ExtensionClasses.scala
@@ -0,0 +1,14 @@
+object ExtensionClasses extends App {
+  case class Circle(x: Double, y: Double, radius: Double)
+
+  // New Scala 3 way:
+  def (c: Circle) circumference: Double = c.radius * math.Pi * 2
+
+  val value = Circle(0, 0, 0.5).circumference
+  println(s"circumference = $value")
+
+  // Scala 2 way
+  //implicit class CircleOps(circle: Circle) extends AnyVal {
+  //  def circumference = circle.radius * Pi * 2
+  //}
+}

From a75eb03a288320014ec8ff59c66ac1c050987d79 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Mon, 25 Nov 2019 16:25:35 -0500
Subject: [PATCH 20/59] -

---
 project/build.properties              |  2 +-
 src/main/scala/ExtensionClasses.scala | 22 +++++++++++++++++++---
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/project/build.properties b/project/build.properties
index 5a9ed92..c0bab04 100644
--- a/project/build.properties
+++ b/project/build.properties
@@ -1 +1 @@
-sbt.version=1.3.4
+sbt.version=1.2.8
diff --git a/src/main/scala/ExtensionClasses.scala b/src/main/scala/ExtensionClasses.scala
index 3ec3e75..50767e9 100644
--- a/src/main/scala/ExtensionClasses.scala
+++ b/src/main/scala/ExtensionClasses.scala
@@ -1,14 +1,30 @@
-object ExtensionClasses extends App {
+/** See https://dotty.epfl.ch/docs/reference/contextual/extension-methods-new.html */
+object ExtensionClasses1 extends App {
   case class Circle(x: Double, y: Double, radius: Double)
 
   // New Scala 3 way:
   def (c: Circle) circumference: Double = c.radius * math.Pi * 2
 
-  val value = Circle(0, 0, 0.5).circumference
-  println(s"circumference = $value")
+  val circle = Circle(0, 0, 0.5)
+  println(s"circumference = ${ circle.circumference }")
+
+  assert(circle.circumference == circumference(circle))
 
   // Scala 2 way
   //implicit class CircleOps(circle: Circle) extends AnyVal {
   //  def circumference = circle.radius * Pi * 2
   //}
 }
+
+object ExtensionClasses2 extends App {
+  trait StringSeqOps {
+    def (xs: Seq[String]) longestStrings = {
+      val maxLength = xs.map(_.length).max
+      xs.filter(_.length == maxLength)
+    }
+  }
+
+  given ops1: StringSeqOps
+
+  println(s"""List("here", "is", "a", "list").longestStrings: """ + List("here", "is", "a", "list").longestStrings)
+}

From e9e3d669e283e7b08de1ba510f1cd4e3889716b1 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Mon, 25 Nov 2019 16:38:07 -0500
Subject: [PATCH 21/59] -

---
 src/main/scala/AutoParamTupling.scala    | 1 +
 src/main/scala/ContextQueries.scala      | 1 +
 src/main/scala/Conversion.scala          | 2 ++
 src/main/scala/EnumTypes.scala           | 2 ++
 src/main/scala/ImpliedInstances.scala    | 2 ++
 src/main/scala/IntersectionTypes.scala   | 2 ++
 src/main/scala/MultiversalEquality.scala | 2 ++
 src/main/scala/NamedTypeArguments.scala  | 2 ++
 src/main/scala/PatternMatching.scala     | 2 ++
 src/main/scala/StructuralTypes.scala     | 2 ++
 src/main/scala/TraitParams.scala         | 2 ++
 src/main/scala/TypeLambdas.scala         | 2 ++
 src/main/scala/Typeclasses.scala         | 2 ++
 src/main/scala/UnionTypes.scala          | 2 ++
 14 files changed, 26 insertions(+)

diff --git a/src/main/scala/AutoParamTupling.scala b/src/main/scala/AutoParamTupling.scala
index c7a1e76..478d486 100644
--- a/src/main/scala/AutoParamTupling.scala
+++ b/src/main/scala/AutoParamTupling.scala
@@ -13,4 +13,5 @@ object AutoParamTupling extends App {
       * Consider a pattern matching anonymous function, `{ case (s, i) =>  ... }` */
     xs.zipWithIndex.map((s, i) => println(s"$i: $s"))
   }
+  test
 }
diff --git a/src/main/scala/ContextQueries.scala b/src/main/scala/ContextQueries.scala
index a8c810e..60baa1d 100644
--- a/src/main/scala/ContextQueries.scala
+++ b/src/main/scala/ContextQueries.scala
@@ -41,4 +41,5 @@ object ContextQueries extends App {
     println(parse.sumStrings("3", "4"))
     println(parse.sumStrings("3", "a"))
   }
+  test
 }
diff --git a/src/main/scala/Conversion.scala b/src/main/scala/Conversion.scala
index a60de3c..ec65bca 100644
--- a/src/main/scala/Conversion.scala
+++ b/src/main/scala/Conversion.scala
@@ -30,4 +30,6 @@ object Conversion extends App {
     println(useConversion)
     println(convert(new IntWrapper(42)))
   }
+
+  test
 }
diff --git a/src/main/scala/EnumTypes.scala b/src/main/scala/EnumTypes.scala
index f6c567f..da084b0 100644
--- a/src/main/scala/EnumTypes.scala
+++ b/src/main/scala/EnumTypes.scala
@@ -37,4 +37,6 @@ object EnumTypes extends App {
 
     calculateEarthWeightOnPlanets(80)
   }
+  
+  test
 }
diff --git a/src/main/scala/ImpliedInstances.scala b/src/main/scala/ImpliedInstances.scala
index 700682a..9cdcd8f 100644
--- a/src/main/scala/ImpliedInstances.scala
+++ b/src/main/scala/ImpliedInstances.scala
@@ -34,4 +34,6 @@ object ImpliedInstances extends App {
     println(spoi.parse("21a"))
     println(StringParser.optionParser[Int].parse("42"))
   }
+
+  test
 }
diff --git a/src/main/scala/IntersectionTypes.scala b/src/main/scala/IntersectionTypes.scala
index ea80de3..ceae350 100644
--- a/src/main/scala/IntersectionTypes.scala
+++ b/src/main/scala/IntersectionTypes.scala
@@ -29,4 +29,6 @@ object IntersectionTypes extends App {
     val p2: PP = Point(6, 8)
     println(euclideanDistance(p1, p2))
   }
+
+  test
 }
diff --git a/src/main/scala/MultiversalEquality.scala b/src/main/scala/MultiversalEquality.scala
index 879838b..df317d4 100644
--- a/src/main/scala/MultiversalEquality.scala
+++ b/src/main/scala/MultiversalEquality.scala
@@ -38,4 +38,6 @@ import scala.language.strictEquality
     println("a != b: " + (a != b))
     println("b == a: " + (b == a))
   }
+
+  test
 }
diff --git a/src/main/scala/NamedTypeArguments.scala b/src/main/scala/NamedTypeArguments.scala
index a2ecb5d..bb7402f 100644
--- a/src/main/scala/NamedTypeArguments.scala
+++ b/src/main/scala/NamedTypeArguments.scala
@@ -25,4 +25,6 @@ object NamedTypeArguments extends App {
 
     println(compile)
   }
+
+  test
 }
diff --git a/src/main/scala/PatternMatching.scala b/src/main/scala/PatternMatching.scala
index 14b77c8..f126eb2 100644
--- a/src/main/scala/PatternMatching.scala
+++ b/src/main/scala/PatternMatching.scala
@@ -87,4 +87,6 @@ object PatternMatching extends App {
       case _ => println("empty name")
     }
   }
+
+  test
 }
diff --git a/src/main/scala/StructuralTypes.scala b/src/main/scala/StructuralTypes.scala
index 06223d9..2f46280 100644
--- a/src/main/scala/StructuralTypes.scala
+++ b/src/main/scala/StructuralTypes.scala
@@ -20,4 +20,6 @@ object StructuralTypes extends App {
     // age field is java.util.NoSuchElementException: None.get
     //println(invalidPerson.age)
   }
+
+  test
 }
diff --git a/src/main/scala/TraitParams.scala b/src/main/scala/TraitParams.scala
index c750bd7..32db613 100644
--- a/src/main/scala/TraitParams.scala
+++ b/src/main/scala/TraitParams.scala
@@ -16,4 +16,6 @@ object TraitParams extends App {
 
     x(1)
   }
+
+  test
 }
diff --git a/src/main/scala/TypeLambdas.scala b/src/main/scala/TypeLambdas.scala
index be1caa9..32dd5c8 100644
--- a/src/main/scala/TypeLambdas.scala
+++ b/src/main/scala/TypeLambdas.scala
@@ -11,4 +11,6 @@ object TypeLambdas extends App {
     val tuple: Tuple[String] = ("a", "b")
     println(tuple)
   }
+
+  test
 }
diff --git a/src/main/scala/Typeclasses.scala b/src/main/scala/Typeclasses.scala
index 92d6035..42e5f99 100644
--- a/src/main/scala/Typeclasses.scala
+++ b/src/main/scala/Typeclasses.scala
@@ -13,4 +13,6 @@ object Typeclasses extends App {
     xs.foldLeft(summon[Monoid[T]].unit)(_.combine(_))
 
   def test: Unit = println("""sum("a", "b", "c"): """ + sum(List("a", "b", "c")))
+
+  test
 }
diff --git a/src/main/scala/UnionTypes.scala b/src/main/scala/UnionTypes.scala
index 91146c2..43a0045 100644
--- a/src/main/scala/UnionTypes.scala
+++ b/src/main/scala/UnionTypes.scala
@@ -37,4 +37,6 @@ object UnionTypes extends App {
     println(list)
     println(emptyList)
   }
+
+  test
 }

From be497ca38d9f56970a4cd0207c23db8de18ce2fc Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 12:29:20 -0500
Subject: [PATCH 22/59] -

---
 src/main/scala/AutoParamTupling.scala |  5 ++---
 src/main/scala/ContextQueries.scala   |  3 ++-
 src/main/scala/ContextQueries2.scala  | 25 +++++++++++++++++++++++++
 src/main/scala/ExtensionClasses.scala |  4 ++--
 4 files changed, 31 insertions(+), 6 deletions(-)
 create mode 100644 src/main/scala/ContextQueries2.scala

diff --git a/src/main/scala/AutoParamTupling.scala b/src/main/scala/AutoParamTupling.scala
index 478d486..18825f6 100644
--- a/src/main/scala/AutoParamTupling.scala
+++ b/src/main/scala/AutoParamTupling.scala
@@ -1,6 +1,4 @@
-/**
-  * Automatic Tupling of Function Params: https://dotty.epfl.ch/docs/reference/other-new-features/auto-parameter-tupling.html
-  */
+/** Automatic Tupling of Function Params: https://dotty.epfl.ch/docs/reference/other-new-features/auto-parameter-tupling.html */
 object AutoParamTupling extends App {
   def test: Unit = {
     /** In order to get thread safety, you need to put @volatile before lazy vals.
@@ -13,5 +11,6 @@ object AutoParamTupling extends App {
       * Consider a pattern matching anonymous function, `{ case (s, i) =>  ... }` */
     xs.zipWithIndex.map((s, i) => println(s"$i: $s"))
   }
+
   test
 }
diff --git a/src/main/scala/ContextQueries.scala b/src/main/scala/ContextQueries.scala
index 60baa1d..8ea8f8b 100644
--- a/src/main/scala/ContextQueries.scala
+++ b/src/main/scala/ContextQueries.scala
@@ -3,7 +3,7 @@ import scala.concurrent.{ExecutionContext, Future}
 import scala.util.Try
 
 /** Context Queries (Formerly known as Implicit Function Types):
-  * - http://dotty.epfl.ch/docs/reference/contextual/query-types.html,
+  * - http://dotty.epfl.ch/docs/reference/contextual/implicit-function-types.html,
   * - https://www.scala-lang.org/blog/2016/12/07/implicit-function-types.html */
 object ContextQueries extends App {
   object context {
@@ -41,5 +41,6 @@ object ContextQueries extends App {
     println(parse.sumStrings("3", "4"))
     println(parse.sumStrings("3", "a"))
   }
+
   test
 }
diff --git a/src/main/scala/ContextQueries2.scala b/src/main/scala/ContextQueries2.scala
new file mode 100644
index 0000000..84b2e20
--- /dev/null
+++ b/src/main/scala/ContextQueries2.scala
@@ -0,0 +1,25 @@
+/** This example combines opaque aliases, implicit function types, and extension methods to provide
+  * a zero-overhead abstraction at runtime.
+  * See http://dotty.epfl.ch/docs/reference/contextual/implicit-function-types.html#example-postconditions */
+object PostConditions {
+  opaque type WrappedResult[T] = T
+
+  def result[T](given r: WrappedResult[T]): T = r
+
+  /** This extension method accepts an implicit function type called `condition`,
+    * which receives the given instance of type `WrappedResult[T]``.
+    * The given `WrappedResult` instance is passed to the result method.
+    * `WrappedResult` is an opaque type alias, so its values need not be boxed or unboxed.
+    * Because `ensuring` is added as an extension method, its argument also does not need boxing. */
+  def [T](x: T) ensuring(condition: (given WrappedResult[T]) => Boolean): T = {
+    assert(condition(given x))
+    x
+  }
+}
+
+object ContextQueries2 extends App {
+  import PostConditions.{ensuring, result}
+
+  val s = List(1, 2, 3).sum.ensuring(result == 6)
+  println("Yes, the list sums to 6.")
+}
diff --git a/src/main/scala/ExtensionClasses.scala b/src/main/scala/ExtensionClasses.scala
index 50767e9..bdb26e5 100644
--- a/src/main/scala/ExtensionClasses.scala
+++ b/src/main/scala/ExtensionClasses.scala
@@ -2,7 +2,7 @@
 object ExtensionClasses1 extends App {
   case class Circle(x: Double, y: Double, radius: Double)
 
-  // New Scala 3 way:
+  // New Scala 3 way, using an extension method:
   def (c: Circle) circumference: Double = c.radius * math.Pi * 2
 
   val circle = Circle(0, 0, 0.5)
@@ -10,7 +10,7 @@ object ExtensionClasses1 extends App {
 
   assert(circle.circumference == circumference(circle))
 
-  // Scala 2 way
+  // Old Scala 2 way, using an implicit class:
   //implicit class CircleOps(circle: Circle) extends AnyVal {
   //  def circumference = circle.radius * Pi * 2
   //}

From 62e31757e5184e92fca7c3b7085c358b0a8054a7 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 13:14:14 -0500
Subject: [PATCH 23/59] -

---
 src/main/scala/Main.scala        |  2 +
 src/main/scala/OpaqueTypes.scala | 64 ++++++++++++++++++++++++++++++++
 2 files changed, 66 insertions(+)
 create mode 100644 src/main/scala/OpaqueTypes.scala

diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index 30632e6..848ae9e 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -6,6 +6,8 @@ object Main {
     runExample("Context Queries")(ContextQueries.test)
     runExample("Implied Instances")(ImpliedInstances.test)
     runExample("Conversion")(Conversion.test)
+    runExample("OpaqueTypes 1")(OpaqueTypes1.test)
+    runExample("OpaqueTypes 2")(OpaqueTypes2.test)
     runExample("Union Types")(UnionTypes.test)
     runExample("Intersection Types")(IntersectionTypes.test)
     runExample("Type Lambda")(TypeLambdas.test)
diff --git a/src/main/scala/OpaqueTypes.scala b/src/main/scala/OpaqueTypes.scala
new file mode 100644
index 0000000..2a3e9b7
--- /dev/null
+++ b/src/main/scala/OpaqueTypes.scala
@@ -0,0 +1,64 @@
+/** Opaque types aliases provide type abstraction without *any* runtime overhead.
+See https://dotty.epfl.ch/docs/reference/other-new-features/opaques.html */
+object OpaqueTypes1 extends App {
+  object Logarithms {
+    opaque type Logarithm = Double
+
+    object Logarithm {
+      // These are the ways to lift to the logarithm type
+      def apply(d: Double): Logarithm = math.log(d)
+
+      def safe(d: Double): Option[Logarithm] =
+        if (d > 0.0) Some(math.log(d)) else None
+    }
+
+    // Extension methods define opaque types' public APIs
+    given logarithmOps: {
+      def (x: Logarithm) toDouble: Double = math.exp(x)
+      def (x: Logarithm) + (y: Logarithm): Logarithm = Logarithm(math.exp(x) + math.exp(y))
+      def (x: Logarithm) * (y: Logarithm): Logarithm = Logarithm(x + y)
+    }
+  }
+
+  def test: Unit = {
+    import Logarithms._
+
+    println("Logarithm(1.0) * Logarithm(2.0): " + (Logarithm(1.0) * Logarithm(2.0)))
+    println("Logarithm(1.0) + Logarithm(2.0): " + (Logarithm(1.0) + Logarithm(2.0)))
+  }
+
+  test
+}
+
+object OpaqueTypes2 extends App {
+  object Access {
+    opaque type Permissions = Int
+    opaque type PermissionChoice = Int
+    /** `Permission`'s upper bound is `Permissions & PermissionChoice`.
+      * Thus `Permission` is universally known to be a subtype of `Permissions` and `PermissionChoice`. */
+    opaque type Permission <: Permissions & PermissionChoice = Int
+
+    def (x: Permissions) & (y: Permissions): Permissions = x & y
+    def (x: PermissionChoice) | (y: PermissionChoice): PermissionChoice = x | y
+    def (x: Permissions) is (y: Permissions) = (x & y) == y
+    def (x: Permissions) isOneOf (y: PermissionChoice) = (x & y) != 0
+
+    val NoPermission: Permission = 0
+    val ReadOnly: Permission = 1
+    val WriteOnly: Permission = 2
+    val ReadWrite: Permissions = ReadOnly & WriteOnly
+    val ReadOrWrite: PermissionChoice = ReadOnly | WriteOnly
+  }
+
+  def test: Unit = {
+    import Access._
+
+    case class Item(rights: Permissions)
+
+    val x = Item(ReadOnly)
+    assert( x.rights.is(ReadWrite) )
+    assert( x.rights.isOneOf(ReadOrWrite) == true )
+  }
+
+  test
+}

From 004f1134ef28c9aa2285b1e869afeb7894bc0dd6 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 14:04:26 -0500
Subject: [PATCH 24/59] -

---
 src/main/scala/OpaqueTypes.scala | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/main/scala/OpaqueTypes.scala b/src/main/scala/OpaqueTypes.scala
index 2a3e9b7..5ba3de7 100644
--- a/src/main/scala/OpaqueTypes.scala
+++ b/src/main/scala/OpaqueTypes.scala
@@ -46,7 +46,7 @@ object OpaqueTypes2 extends App {
     val NoPermission: Permission = 0
     val ReadOnly: Permission = 1
     val WriteOnly: Permission = 2
-    val ReadWrite: Permissions = ReadOnly & WriteOnly
+    val ReadWrite: Permissions = ReadOnly | WriteOnly
     val ReadOrWrite: PermissionChoice = ReadOnly | WriteOnly
   }
 
@@ -56,8 +56,8 @@ object OpaqueTypes2 extends App {
     case class Item(rights: Permissions)
 
     val x = Item(ReadOnly)
-    assert( x.rights.is(ReadWrite) )
-    assert( x.rights.isOneOf(ReadOrWrite) == true )
+    assert( ! x.rights.is(ReadWrite) )
+    assert( x.rights.isOneOf(ReadOrWrite) )
   }
 
   test

From 80975485645ca6028a2bf36303670d8400f4a6f3 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 14:16:57 -0500
Subject: [PATCH 25/59] -

---
 src/main/scala/OpaqueTypes.scala | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/main/scala/OpaqueTypes.scala b/src/main/scala/OpaqueTypes.scala
index 5ba3de7..199cf8d 100644
--- a/src/main/scala/OpaqueTypes.scala
+++ b/src/main/scala/OpaqueTypes.scala
@@ -34,6 +34,7 @@ object OpaqueTypes2 extends App {
   object Access {
     opaque type Permissions = Int
     opaque type PermissionChoice = Int
+    
     /** `Permission`'s upper bound is `Permissions & PermissionChoice`.
       * Thus `Permission` is universally known to be a subtype of `Permissions` and `PermissionChoice`. */
     opaque type Permission <: Permissions & PermissionChoice = Int

From 6f5dd69519782cc3c0390baaf14c9eafb4fa9965 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 14:25:01 -0500
Subject: [PATCH 26/59] -

---
 .travis.yml |  8 --------
 README.md   | 27 ++++++++++++++++++---------
 2 files changed, 18 insertions(+), 17 deletions(-)
 delete mode 100644 .travis.yml

diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 99c1040..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,8 +0,0 @@
-language: scala
-
-jdk:
-  - openjdk8
-
-script:
-  - sbt run
-  - sbt 'set scalaVersion := dottyLatestNightlyBuild.get' run
diff --git a/README.md b/README.md
index a336d89..b60d8c1 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # Example sbt project that compiles using Dotty
 
-[![Build Status](https://travis-ci.org/lampepfl/dotty-example-project.svg?branch=master)](https://travis-ci.org/lampepfl/dotty-example-project)
+I (Mike Slinn) fixed many significant bugs in the [upstream project](https://github.com/lampepfl/dotty-example-project) and added code examples for new major features that were missing.
 
 ## Usage
 
@@ -21,13 +21,20 @@ that does not work with dotty, try to disable all plugins in
 
 ### IDE support
 
-Dotty comes built-in with IDE support, to try it out see
+> Dotty comes built-in with IDE support, to try it out see
 http://dotty.epfl.ch/docs/usage/ide-support.html
 
+Meh, not so much.
+I found Atom with sbt running in a shell under platformio terminal worked best.
+
 ## Making a new Dotty project
-The fastest way to start a new Dotty project is to use one of the following templates:
-* [Simple Dotty project](https://github.com/lampepfl/dotty.g8)
-* [Dotty project that cross-compiles with Scala 2](https://github.com/lampepfl/dotty-cross.g8)
+> The fastest way to start a new Dotty project is to use one of the following templates:
+> * [Simple Dotty project](https://github.com/lampepfl/dotty.g8)
+> * [Dotty project that cross-compiles with Scala 2](https://github.com/lampepfl/dotty-cross.g8)
+
+I am not a fan of `giter8`.
+There is no reason to introduce yet another obscure language.
+[Try dottyTemplate](https://github.com/mslinn/dottyTemplate) instead.
 
 ## Using Dotty in an existing project
 
@@ -40,11 +47,11 @@ addSbtPlugin("ch.epfl.lamp" % "sbt-dotty" % "0.3.4")
 
 ### project/build.properties
 ```scala
-sbt.version=1.3.4
+sbt.version=1.2.8
 ```
 
-Versions of sbt older than 1.3.3 are not supported.
-
+Versions of sbt older than 1.2.8 are not supported.
+Versions 1.3.2 and 1.3.3 do not work properly with Dotty.
 
 ### build.sbt
 Any version number that starts with `0.` is automatically recognized as Dotty by
@@ -74,9 +81,11 @@ scalacOptions ++= { if (isDotty.value) Seq("-language:Scala2") else Nil }
 Using the `isDotty` setting ensures that this option will only be set when
 compiling with Dotty.
 
-A tool to port code from Scala 2.x to Dotty is currently in development at
+> A tool to port code from Scala 2.x to Dotty is currently in development at
 https://github.com/scalacenter/scalafix
 
+Actually, the truth is `scalafix` has not had any work done on it in a long time, and there is no indication when this important project will get the attention it deserves. I'm concerned that history will repeat itself and we'll get a last-minute hack job.
+
 If your build contains dependencies that have only been published for Scala 2.x,
 you may be able to get them to work on Dotty by replacing:
 

From d746979e759942e17d5a0d2424d4c8b436a8e8e2 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 14:25:58 -0500
Subject: [PATCH 27/59] -

---
 README.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index b60d8c1..386428d 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# Example sbt project that compiles using Dotty
+# Example sbt Project that Compiles Using Dotty
 
 I (Mike Slinn) fixed many significant bugs in the [upstream project](https://github.com/lampepfl/dotty-example-project) and added code examples for new major features that were missing.
 
@@ -51,7 +51,7 @@ sbt.version=1.2.8
 ```
 
 Versions of sbt older than 1.2.8 are not supported.
-Versions 1.3.2 and 1.3.3 do not work properly with Dotty.
+Versions 1.3.3 and 1.3.4 do not work properly with Dotty.
 
 ### build.sbt
 Any version number that starts with `0.` is automatically recognized as Dotty by

From c0fb06940d6e84c2d17c6e5e684c7f33c3bab4ef Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 14:26:33 -0500
Subject: [PATCH 28/59] -

---
 README.md | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 386428d..79e6a7e 100644
--- a/README.md
+++ b/README.md
@@ -68,8 +68,7 @@ https://repo1.maven.org/maven2/ch/epfl/lamp/dotty_0.18/ to find the version
 number for the latest nightly build. Alternatively, you can set `scalaVersion :=
 dottyLatestNightlyBuild.get` to always use the latest nightly build of dotty.
 
-## Getting your project to compile with Dotty
-
+## Compiling Your Project with Dotty
 When porting an existing project, it's a good idea to start out with the Scala 2
 compatibility mode (note that this mode affects typechecking and thus may
 prevent some valid Dotty code from compiling) by adding to your `build.sbt`:

From 366a242812e03823d3d9332c4f7cc7ee117c28e9 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 14:26:52 -0500
Subject: [PATCH 29/59] -

---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 79e6a7e..1f715f9 100644
--- a/README.md
+++ b/README.md
@@ -68,7 +68,7 @@ https://repo1.maven.org/maven2/ch/epfl/lamp/dotty_0.18/ to find the version
 number for the latest nightly build. Alternatively, you can set `scalaVersion :=
 dottyLatestNightlyBuild.get` to always use the latest nightly build of dotty.
 
-## Compiling Your Project with Dotty
+## Compiling Scala 2 Projects with Dotty
 When porting an existing project, it's a good idea to start out with the Scala 2
 compatibility mode (note that this mode affects typechecking and thus may
 prevent some valid Dotty code from compiling) by adding to your `build.sbt`:

From a7a6568bc053a50fceb0d861797284d868d9752e Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 14:27:36 -0500
Subject: [PATCH 30/59] -

---
 README.md | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index 1f715f9..212c11a 100644
--- a/README.md
+++ b/README.md
@@ -19,7 +19,7 @@ If compiling this example project fails, you probably have a global sbt plugin
 that does not work with dotty, try to disable all plugins in
 `~/.sbt/1.0/plugins` and `~/.sbt/1.0`.
 
-### IDE support
+### IDE Support
 
 > Dotty comes built-in with IDE support, to try it out see
 http://dotty.epfl.ch/docs/usage/ide-support.html
@@ -27,7 +27,7 @@ http://dotty.epfl.ch/docs/usage/ide-support.html
 Meh, not so much.
 I found Atom with sbt running in a shell under platformio terminal worked best.
 
-## Making a new Dotty project
+## Making a New Dotty Project
 > The fastest way to start a new Dotty project is to use one of the following templates:
 > * [Simple Dotty project](https://github.com/lampepfl/dotty.g8)
 > * [Dotty project that cross-compiles with Scala 2](https://github.com/lampepfl/dotty-cross.g8)
@@ -36,7 +36,7 @@ I am not a fan of `giter8`.
 There is no reason to introduce yet another obscure language.
 [Try dottyTemplate](https://github.com/mslinn/dottyTemplate) instead.
 
-## Using Dotty in an existing project
+## Using Dotty in An Existing Project
 
 You will need to make the following adjustments to your build:
 
@@ -45,7 +45,7 @@ You will need to make the following adjustments to your build:
 addSbtPlugin("ch.epfl.lamp" % "sbt-dotty" % "0.3.4")
 ```
 
-### project/build.properties
+### `project/build.properties`
 ```scala
 sbt.version=1.2.8
 ```
@@ -53,7 +53,7 @@ sbt.version=1.2.8
 Versions of sbt older than 1.2.8 are not supported.
 Versions 1.3.3 and 1.3.4 do not work properly with Dotty.
 
-### build.sbt
+### `build.sbt`
 Any version number that starts with `0.` is automatically recognized as Dotty by
 the `sbt-dotty` plugin, you don't need to set up anything:
 
@@ -61,7 +61,7 @@ the `sbt-dotty` plugin, you don't need to set up anything:
 scalaVersion := "0.20.0-RC1"
 ```
 
-#### Nightly builds
+#### Nightly Builds
 If the latest release of Dotty is missing a bugfix or feature you need, you may
 wish to use a nightly build. Look at the bottom of
 https://repo1.maven.org/maven2/ch/epfl/lamp/dotty_0.18/ to find the version

From abd66bf5662d4197a1a915cd10fca51e4f074aa5 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 14:29:26 -0500
Subject: [PATCH 31/59] -

---
 README.md | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index 212c11a..f7056cc 100644
--- a/README.md
+++ b/README.md
@@ -4,10 +4,12 @@ I (Mike Slinn) fixed many significant bugs in the [upstream project](https://git
 
 ## Usage
 
-This is a normal sbt project, you can compile code with `sbt compile` and run it
-with `sbt run`, `sbt console` will start a Dotty REPL.
+This is a normal sbt project.
+You can compile code with `sbt compile` and run it
+with `sbt run` or `sbt runMain <entryPoint>`.
+`sbt console` will start a Dotty REPL.
 
-You can run just one example from the `sbt console`, for example we can run `Typeclasses.test`:
+You can also execute just one example from the `sbt console` by evaluating the `test` method, for example we can run `Typeclasses.test`:
 
 ```
 $ sbt console
@@ -16,8 +18,8 @@ sum("a", "b", "c"): abc
 ```
 
 If compiling this example project fails, you probably have a global sbt plugin
-that does not work with dotty, try to disable all plugins in
-`~/.sbt/1.0/plugins` and `~/.sbt/1.0`.
+that does not work with dotty; disable all plugins in
+`~/.sbt/1.0/plugins` and `~/.sbt/1.0` by renaming those directories to something else.
 
 ### IDE Support
 

From 2b733abdb7da0504a389707631a960f6ba986fe7 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 14:30:20 -0500
Subject: [PATCH 32/59] -

---
 README.md | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index f7056cc..a905524 100644
--- a/README.md
+++ b/README.md
@@ -21,7 +21,7 @@ If compiling this example project fails, you probably have a global sbt plugin
 that does not work with dotty; disable all plugins in
 `~/.sbt/1.0/plugins` and `~/.sbt/1.0` by renaming those directories to something else.
 
-### IDE Support
+## IDE Support
 
 > Dotty comes built-in with IDE support, to try it out see
 http://dotty.epfl.ch/docs/usage/ide-support.html
@@ -63,7 +63,7 @@ the `sbt-dotty` plugin, you don't need to set up anything:
 scalaVersion := "0.20.0-RC1"
 ```
 
-#### Nightly Builds
+### Nightly Builds
 If the latest release of Dotty is missing a bugfix or feature you need, you may
 wish to use a nightly build. Look at the bottom of
 https://repo1.maven.org/maven2/ch/epfl/lamp/dotty_0.18/ to find the version
@@ -111,6 +111,5 @@ Alternatively, to set this setting on all your dependencies, you can use:
 ```
 
 ## Discuss
-
-Feel free to come chat with us on the
+Feel free to come chat on the
 [Dotty gitter](http://gitter.im/lampepfl/dotty)!

From 477c53b99d88050193e21453d2504ed3fc3ff937 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 14:30:35 -0500
Subject: [PATCH 33/59] -

---
 src/main/scala/ContextQueries.scala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/scala/ContextQueries.scala b/src/main/scala/ContextQueries.scala
index 8ea8f8b..2f124d6 100644
--- a/src/main/scala/ContextQueries.scala
+++ b/src/main/scala/ContextQueries.scala
@@ -5,7 +5,7 @@ import scala.util.Try
 /** Context Queries (Formerly known as Implicit Function Types):
   * - http://dotty.epfl.ch/docs/reference/contextual/implicit-function-types.html,
   * - https://www.scala-lang.org/blog/2016/12/07/implicit-function-types.html */
-object ContextQueries extends App {
+object ContextQueries1 extends App {
   object context {
     // type alias Contextual
     type Contextual[T] = (given ExecutionContext) => T

From 9f894dce624d96fb081f7290b347bed232329632 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 14:32:23 -0500
Subject: [PATCH 34/59] -

---
 src/main/scala/ContextQueries2.scala | 6 ++++--
 src/main/scala/Main.scala            | 3 ++-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/main/scala/ContextQueries2.scala b/src/main/scala/ContextQueries2.scala
index 84b2e20..d39e671 100644
--- a/src/main/scala/ContextQueries2.scala
+++ b/src/main/scala/ContextQueries2.scala
@@ -20,6 +20,8 @@ object PostConditions {
 object ContextQueries2 extends App {
   import PostConditions.{ensuring, result}
 
-  val s = List(1, 2, 3).sum.ensuring(result == 6)
-  println("Yes, the list sums to 6.")
+  def test: Unit = {
+    val s = List(1, 2, 3).sum.ensuring(result == 6)
+    println("Yes, the list sums to 6.")
+  }
 }
diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index 848ae9e..76dfffe 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -3,7 +3,8 @@ object Main {
     runExample("Typeclasses")(Typeclasses.test)
     runExample("Trait Params")(TraitParams.test)
     runExample("Enum Types")(EnumTypes.test)
-    runExample("Context Queries")(ContextQueries.test)
+    runExample("Context Queries 1")(ContextQueries1.test)
+    runExample("Context Queries 2")(ContextQueries2.test)
     runExample("Implied Instances")(ImpliedInstances.test)
     runExample("Conversion")(Conversion.test)
     runExample("OpaqueTypes 1")(OpaqueTypes1.test)

From 9990ba0d778e91cc7169fda8237c164f357e3b60 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 14:32:42 -0500
Subject: [PATCH 35/59] -

---
 src/main/scala/{ContextQueries.scala => ContextQueries1.scala} | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 rename src/main/scala/{ContextQueries.scala => ContextQueries1.scala} (100%)

diff --git a/src/main/scala/ContextQueries.scala b/src/main/scala/ContextQueries1.scala
similarity index 100%
rename from src/main/scala/ContextQueries.scala
rename to src/main/scala/ContextQueries1.scala

From 139dd8e5786f1c3b7bddeb8bcecec57e32f55638 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 14:59:52 -0500
Subject: [PATCH 36/59] -

---
 src/main/scala/Main.scala        | 14 +++++++-------
 src/main/scala/TraitParams.scala | 20 ++++++++++----------
 src/main/scala/UnionTypes.scala  |  3 +--
 3 files changed, 18 insertions(+), 19 deletions(-)

diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index 76dfffe..951df2d 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -1,22 +1,22 @@
 object Main {
   def main(args: Array[String]): Unit = {
-    runExample("Typeclasses")(Typeclasses.test)
     runExample("Trait Params")(TraitParams.test)
-    runExample("Enum Types")(EnumTypes.test)
+    runExample("Typeclasses")(Typeclasses.test)
+    runExample("OpaqueTypes 1")(OpaqueTypes1.test)
     runExample("Context Queries 1")(ContextQueries1.test)
+    runExample("Intersection Types")(IntersectionTypes.test)
     runExample("Context Queries 2")(ContextQueries2.test)
-    runExample("Implied Instances")(ImpliedInstances.test)
-    runExample("Conversion")(Conversion.test)
-    runExample("OpaqueTypes 1")(OpaqueTypes1.test)
     runExample("OpaqueTypes 2")(OpaqueTypes2.test)
-    runExample("Union Types")(UnionTypes.test)
-    runExample("Intersection Types")(IntersectionTypes.test)
     runExample("Type Lambda")(TypeLambdas.test)
+    runExample("Enum Types")(EnumTypes.test)
+    runExample("Implied Instances")(ImpliedInstances.test)
+    runExample("Conversion")(Conversion.test)
     runExample("Multiversal Equality")(MultiversalEquality.test)
     runExample("Named Type Arguments")(NamedTypeArguments.test)
     runExample("Auto Param Tupling")(AutoParamTupling.test)
     runExample("Structural Types")(StructuralTypes.test)
     runExample("Pattern Matching")(PatternMatching.test)
+    runExample("Union Types")(UnionTypes.test)
   }
 
   private def runExample(name: String)
diff --git a/src/main/scala/TraitParams.scala b/src/main/scala/TraitParams.scala
index 32db613..ef4f2ee 100644
--- a/src/main/scala/TraitParams.scala
+++ b/src/main/scala/TraitParams.scala
@@ -1,20 +1,20 @@
 /** Trait Parameters: https://dotty.epfl.ch/docs/reference/other-new-features/trait-parameters.html */
 object TraitParams extends App {
   trait Base(val msg: String)
+  
   class A extends Base("Hello")
-  class B extends Base("Dotty!")
+  class B extends Base("Dotty")
 
-  // Union types only exist in Dotty, so there's no chance that this will accidentally be compiled with Scala 2
-  private def printMessages(msgs: (A | B)*): Unit = println(msgs.map(_.msg).mkString(" "))
+  case class C(override val msg: String) extends Base(msg)
+  case class D(override val msg: String) extends Base(msg)
 
-  def test: Unit = {
-    printMessages(new A, new B)
-
-    // Sanity check the classpath: this won't run if the dotty jar is not present.
-    val x: Int => Int =
-      z => z
+  /** @param msgs varargs union type (sequence of A or B) */
+  private def printMessages1(msgs: (A | B)*): Unit = println(msgs.map(_.msg).mkString(" ") + "!")
+  private def printMessages2(msgs: (C | D)*): Unit = println(msgs.map(_.msg).mkString(" ") + "!")
 
-    x(1)
+  def test: Unit = {
+    printMessages1(new A, new B)
+    printMessages2(C("Goodbye"), D("cruel world"))
   }
 
   test
diff --git a/src/main/scala/UnionTypes.scala b/src/main/scala/UnionTypes.scala
index 43a0045..c909a4b 100644
--- a/src/main/scala/UnionTypes.scala
+++ b/src/main/scala/UnionTypes.scala
@@ -11,9 +11,8 @@ object UnionTypes extends App {
   final class Empty extends List[Nothing]
   final case class Cons[+A](h: A, t: List[A]) extends List[A]
 
-  private def safeDivide(a: Double, b: Double): DivisionResult = {
+  private def safeDivide(a: Double, b: Double): DivisionResult =
     if (b == 0) DivisionByZero("DivisionByZeroException") else Success(a / b)
-  }
 
   private def either(division: Division) = division match {
     case DivisionByZero(m) => Left(m)

From c65727b6d47980763a60671ba1974c571105c2d5 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 15:09:34 -0500
Subject: [PATCH 37/59] -

---
 src/main/scala/TraitParams.scala |  8 +++++---
 src/main/scala/UnionTypes.scala  | 17 ++++++++++-------
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/src/main/scala/TraitParams.scala b/src/main/scala/TraitParams.scala
index ef4f2ee..6d17c9e 100644
--- a/src/main/scala/TraitParams.scala
+++ b/src/main/scala/TraitParams.scala
@@ -1,15 +1,17 @@
 /** Trait Parameters: https://dotty.epfl.ch/docs/reference/other-new-features/trait-parameters.html */
 object TraitParams extends App {
   trait Base(val msg: String)
-  
+
   class A extends Base("Hello")
   class B extends Base("Dotty")
 
+  /** @param msgs varargs union type (sequence of A or B) */
+  private def printMessages1(msgs: (A | B)*): Unit = println(msgs.map(_.msg).mkString(" ") + "!")
+
+
   case class C(override val msg: String) extends Base(msg)
   case class D(override val msg: String) extends Base(msg)
 
-  /** @param msgs varargs union type (sequence of A or B) */
-  private def printMessages1(msgs: (A | B)*): Unit = println(msgs.map(_.msg).mkString(" ") + "!")
   private def printMessages2(msgs: (C | D)*): Unit = println(msgs.map(_.msg).mkString(" ") + "!")
 
   def test: Unit = {
diff --git a/src/main/scala/UnionTypes.scala b/src/main/scala/UnionTypes.scala
index c909a4b..2669d59 100644
--- a/src/main/scala/UnionTypes.scala
+++ b/src/main/scala/UnionTypes.scala
@@ -1,15 +1,17 @@
-/** Union Types: https://dotty.epfl.ch/docs/reference/new-types/union-types.html */
+/** Union types (aka sum types): https://dotty.epfl.ch/docs/reference/new-types/union-types.html */
 object UnionTypes extends App {
   sealed trait Division
   final case class DivisionByZero(msg: String) extends Division
   final case class Success(double: Double) extends Division
 
-  // You can create type aliases for your union types (sum types).
+  // Type aliases can use union types
   type DivisionResult = DivisionByZero | Success
 
   sealed trait List[+A]
-  final class Empty extends List[Nothing]
   final case class Cons[+A](h: A, t: List[A]) extends List[A]
+  final class Empty extends List[Nothing] {
+    override def toString: String = "Empty"
+  }
 
   private def safeDivide(a: Double, b: Double): DivisionResult =
     if (b == 0) DivisionByZero("DivisionByZeroException") else Success(a / b)
@@ -26,15 +28,16 @@ object UnionTypes extends App {
     val divisionResultFailure: Success | DivisionByZero = safeDivide(4, 0)
 
     // Calling `either` function with union typed value.
-    println(either(divisionResultSuccess))
+    println("either(divisionResultSuccess): " + either(divisionResultSuccess))
 
     // Calling `either` function with union typed value.
-    println(either(divisionResultFailure))
+    println("either(divisionResultFailure): " + either(divisionResultFailure))
 
     val list: Cons[Int] | Empty = Cons(1, Cons(2, Cons(3, Empty())))
+    println("list: " + list)
+
     val emptyList: Empty | Cons[Any] = Empty()
-    println(list)
-    println(emptyList)
+    println("emptyList: " + emptyList)
   }
 
   test

From 706296dd179cb6ff07842a905d4b0de5e4b90555 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 15:23:16 -0500
Subject: [PATCH 38/59] -

---
 src/main/scala/EnumTypes.scala        | 7 +++++--
 src/main/scala/ExtensionClasses.scala | 3 ++-
 src/main/scala/OpaqueTypes.scala      | 5 +++--
 src/main/scala/Typeclasses.scala      | 6 ++++++
 src/main/scala/UnionTypes.scala       | 7 ++++++-
 5 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/src/main/scala/EnumTypes.scala b/src/main/scala/EnumTypes.scala
index da084b0..042d8f4 100644
--- a/src/main/scala/EnumTypes.scala
+++ b/src/main/scala/EnumTypes.scala
@@ -1,4 +1,7 @@
-/** Enum Types: http://dotty.epfl.ch/docs/reference/enums/adts.html */
+/** Proper Scala enums (Scala 2 Enumerations are horrible).
+  * * Interoperate with Java enums
+  * * Support Algebraic Data Types (ADTs) because they accept type parameters, and can be Generalized ADTs (GADTs).
+  * See http://dotty.epfl.ch/docs/reference/enums/adts.html */
 object EnumTypes extends App {
   enum ListEnum[+A] {
     case Cons(h: A, t: ListEnum[A])
@@ -37,6 +40,6 @@ object EnumTypes extends App {
 
     calculateEarthWeightOnPlanets(80)
   }
-  
+
   test
 }
diff --git a/src/main/scala/ExtensionClasses.scala b/src/main/scala/ExtensionClasses.scala
index bdb26e5..d70b872 100644
--- a/src/main/scala/ExtensionClasses.scala
+++ b/src/main/scala/ExtensionClasses.scala
@@ -1,4 +1,5 @@
-/** See https://dotty.epfl.ch/docs/reference/contextual/extension-methods-new.html */
+/** Easy way to add methods to existing classes
+  * See https://dotty.epfl.ch/docs/reference/contextual/extension-methods-new.html */
 object ExtensionClasses1 extends App {
   case class Circle(x: Double, y: Double, radius: Double)
 
diff --git a/src/main/scala/OpaqueTypes.scala b/src/main/scala/OpaqueTypes.scala
index 199cf8d..c099183 100644
--- a/src/main/scala/OpaqueTypes.scala
+++ b/src/main/scala/OpaqueTypes.scala
@@ -1,5 +1,6 @@
 /** Opaque types aliases provide type abstraction without *any* runtime overhead.
-See https://dotty.epfl.ch/docs/reference/other-new-features/opaques.html */
+  * Replace Scala 2 value types
+  * See https://dotty.epfl.ch/docs/reference/other-new-features/opaques.html */
 object OpaqueTypes1 extends App {
   object Logarithms {
     opaque type Logarithm = Double
@@ -34,7 +35,7 @@ object OpaqueTypes2 extends App {
   object Access {
     opaque type Permissions = Int
     opaque type PermissionChoice = Int
-    
+
     /** `Permission`'s upper bound is `Permissions & PermissionChoice`.
       * Thus `Permission` is universally known to be a subtype of `Permissions` and `PermissionChoice`. */
     opaque type Permission <: Permissions & PermissionChoice = Int
diff --git a/src/main/scala/Typeclasses.scala b/src/main/scala/Typeclasses.scala
index 42e5f99..10dd307 100644
--- a/src/main/scala/Typeclasses.scala
+++ b/src/main/scala/Typeclasses.scala
@@ -1,3 +1,9 @@
+/** Extension methods provide a nice syntax for typeclasses
+  * * Removes need for dangerous implicit conversions
+  * * Emphasize intent over mechanism
+  * * Better error messages than generated from implicits
+  * * Implicit conversions will go away
+  * See https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/delegates */
 object Typeclasses extends App {
   trait SemiGroup[T] with
     def (x: T) combine (y: T): T
diff --git a/src/main/scala/UnionTypes.scala b/src/main/scala/UnionTypes.scala
index 2669d59..52beebf 100644
--- a/src/main/scala/UnionTypes.scala
+++ b/src/main/scala/UnionTypes.scala
@@ -1,4 +1,9 @@
-/** Union types (aka sum types): https://dotty.epfl.ch/docs/reference/new-types/union-types.html */
+/** Union types (aka sum types):
+  * * Like C structs
+  * * No boxing/unboxing overhead
+  * * Works with singleton types
+  * * Good for Scala/JavaScript interoperability
+  * https://dotty.epfl.ch/docs/reference/new-types/union-types.html */
 object UnionTypes extends App {
   sealed trait Division
   final case class DivisionByZero(msg: String) extends Division

From 67649f81b820d73c28fd49e913ab928c58a76b39 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 15:28:26 -0500
Subject: [PATCH 39/59] -

---
 README.md | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index a905524..b7acf56 100644
--- a/README.md
+++ b/README.md
@@ -27,7 +27,7 @@ that does not work with dotty; disable all plugins in
 http://dotty.epfl.ch/docs/usage/ide-support.html
 
 Meh, not so much.
-I found Atom with sbt running in a shell under platformio terminal worked best.
+I found Atom with sbt running in a shell under `platformio-ide-terminal` worked best.
 
 ## Making a New Dotty Project
 > The fastest way to start a new Dotty project is to use one of the following templates:
@@ -111,5 +111,4 @@ Alternatively, to set this setting on all your dependencies, you can use:
 ```
 
 ## Discuss
-Feel free to come chat on the
-[Dotty gitter](http://gitter.im/lampepfl/dotty)!
+Chat on the [Dotty gitter](http://gitter.im/lampepfl/dotty) channel.

From 4019e5caa24e4ec082c77b82a3cc1745fdd60583 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 15:43:28 -0500
Subject: [PATCH 40/59] -

---
 src/main/scala/ContextQueries1.scala | 14 +++---
 src/main/scala/EnumTypes.scala       |  1 +
 src/main/scala/OpaqueTypes.scala     | 66 ----------------------------
 src/main/scala/OpaqueTypes1.scala    | 32 ++++++++++++++
 src/main/scala/OpaqueTypes2.scala    | 33 ++++++++++++++
 5 files changed, 74 insertions(+), 72 deletions(-)
 delete mode 100644 src/main/scala/OpaqueTypes.scala
 create mode 100644 src/main/scala/OpaqueTypes1.scala
 create mode 100644 src/main/scala/OpaqueTypes2.scala

diff --git a/src/main/scala/ContextQueries1.scala b/src/main/scala/ContextQueries1.scala
index 2f124d6..7242732 100644
--- a/src/main/scala/ContextQueries1.scala
+++ b/src/main/scala/ContextQueries1.scala
@@ -3,8 +3,10 @@ import scala.concurrent.{ExecutionContext, Future}
 import scala.util.Try
 
 /** Context Queries (Formerly known as Implicit Function Types):
+  * - Implicit functions are functions that only have implicit parameters.
+  * - Their types are implicit function types.
   * - http://dotty.epfl.ch/docs/reference/contextual/implicit-function-types.html,
-  * - https://www.scala-lang.org/blog/2016/12/07/implicit-function-types.html */
+  * - Old syntax: https://www.scala-lang.org/blog/2016/12/07/implicit-function-types.html */
 object ContextQueries1 extends App {
   object context {
     // type alias Contextual
@@ -14,7 +16,7 @@ object ContextQueries1 extends App {
     def asyncSum(x: Int, y: Int): Contextual[Future[Int]] = Future(x + y)
 
     def asyncMult(x: Int, y: Int)
-                 (given ctx: ExecutionContext) = Future(x * y)
+                 (given ctx: ExecutionContext): Contextual[Future[Int]] = Future(x * y)
   }
 
   object parse {
@@ -35,11 +37,11 @@ object ContextQueries1 extends App {
   def test: Unit = {
     import ExecutionContext.Implicits.global
 
-    context.asyncSum(3, 4).foreach(println)
-    context.asyncMult(3, 4).foreach(println)
+    context.asyncSum(3, 4).foreach(x => println("asyncSum: " + x))
+    context.asyncMult(3, 4).foreach(x => println("asyncMult: " + x))
 
-    println(parse.sumStrings("3", "4"))
-    println(parse.sumStrings("3", "a"))
+    println("""parse.sumStrings("3", "4"): """ + parse.sumStrings("3", "4"))
+    println("""parse.sumStrings("3", "a"): """ + parse.sumStrings("3", "a"))
   }
 
   test
diff --git a/src/main/scala/EnumTypes.scala b/src/main/scala/EnumTypes.scala
index 042d8f4..139e8e0 100644
--- a/src/main/scala/EnumTypes.scala
+++ b/src/main/scala/EnumTypes.scala
@@ -8,6 +8,7 @@ object EnumTypes extends App {
     case Empty
   }
 
+  /** This looks a lot like the [old Java enum example](https://docs.oracle.com/javase/tutorial/java/javaOO/enum.html) */
   enum Planet(mass: Double, radius: Double) {
     private final val G = 6.67300E-11
 
diff --git a/src/main/scala/OpaqueTypes.scala b/src/main/scala/OpaqueTypes.scala
deleted file mode 100644
index c099183..0000000
--- a/src/main/scala/OpaqueTypes.scala
+++ /dev/null
@@ -1,66 +0,0 @@
-/** Opaque types aliases provide type abstraction without *any* runtime overhead.
-  * Replace Scala 2 value types
-  * See https://dotty.epfl.ch/docs/reference/other-new-features/opaques.html */
-object OpaqueTypes1 extends App {
-  object Logarithms {
-    opaque type Logarithm = Double
-
-    object Logarithm {
-      // These are the ways to lift to the logarithm type
-      def apply(d: Double): Logarithm = math.log(d)
-
-      def safe(d: Double): Option[Logarithm] =
-        if (d > 0.0) Some(math.log(d)) else None
-    }
-
-    // Extension methods define opaque types' public APIs
-    given logarithmOps: {
-      def (x: Logarithm) toDouble: Double = math.exp(x)
-      def (x: Logarithm) + (y: Logarithm): Logarithm = Logarithm(math.exp(x) + math.exp(y))
-      def (x: Logarithm) * (y: Logarithm): Logarithm = Logarithm(x + y)
-    }
-  }
-
-  def test: Unit = {
-    import Logarithms._
-
-    println("Logarithm(1.0) * Logarithm(2.0): " + (Logarithm(1.0) * Logarithm(2.0)))
-    println("Logarithm(1.0) + Logarithm(2.0): " + (Logarithm(1.0) + Logarithm(2.0)))
-  }
-
-  test
-}
-
-object OpaqueTypes2 extends App {
-  object Access {
-    opaque type Permissions = Int
-    opaque type PermissionChoice = Int
-
-    /** `Permission`'s upper bound is `Permissions & PermissionChoice`.
-      * Thus `Permission` is universally known to be a subtype of `Permissions` and `PermissionChoice`. */
-    opaque type Permission <: Permissions & PermissionChoice = Int
-
-    def (x: Permissions) & (y: Permissions): Permissions = x & y
-    def (x: PermissionChoice) | (y: PermissionChoice): PermissionChoice = x | y
-    def (x: Permissions) is (y: Permissions) = (x & y) == y
-    def (x: Permissions) isOneOf (y: PermissionChoice) = (x & y) != 0
-
-    val NoPermission: Permission = 0
-    val ReadOnly: Permission = 1
-    val WriteOnly: Permission = 2
-    val ReadWrite: Permissions = ReadOnly | WriteOnly
-    val ReadOrWrite: PermissionChoice = ReadOnly | WriteOnly
-  }
-
-  def test: Unit = {
-    import Access._
-
-    case class Item(rights: Permissions)
-
-    val x = Item(ReadOnly)
-    assert( ! x.rights.is(ReadWrite) )
-    assert( x.rights.isOneOf(ReadOrWrite) )
-  }
-
-  test
-}
diff --git a/src/main/scala/OpaqueTypes1.scala b/src/main/scala/OpaqueTypes1.scala
new file mode 100644
index 0000000..6ec2bcc
--- /dev/null
+++ b/src/main/scala/OpaqueTypes1.scala
@@ -0,0 +1,32 @@
+/** Opaque types aliases provide type abstraction without *any* runtime overhead.
+  * They replace Scala 2 value types.
+  * See https://dotty.epfl.ch/docs/reference/other-new-features/opaques.html */
+object OpaqueTypes1 extends App {
+  object Logarithms {
+    opaque type Logarithm = Double
+
+    object Logarithm {
+      // These are the ways to lift to the logarithm type
+      def apply(d: Double): Logarithm = math.log(d)
+
+      def safe(d: Double): Option[Logarithm] =
+        if (d > 0.0) Some(math.log(d)) else None
+    }
+
+    // Extension methods define opaque types' public APIs
+    given logarithmOps: {
+      def (x: Logarithm) toDouble: Double = math.exp(x)
+      def (x: Logarithm) + (y: Logarithm): Logarithm = Logarithm(math.exp(x) + math.exp(y))
+      def (x: Logarithm) * (y: Logarithm): Logarithm = Logarithm(x + y)
+    }
+  }
+
+  def test: Unit = {
+    import Logarithms._
+
+    println("Logarithm(1.0) * Logarithm(2.0): " + (Logarithm(1.0) * Logarithm(2.0)))
+    println("Logarithm(1.0) + Logarithm(2.0): " + (Logarithm(1.0) + Logarithm(2.0)))
+  }
+
+  test
+}
diff --git a/src/main/scala/OpaqueTypes2.scala b/src/main/scala/OpaqueTypes2.scala
new file mode 100644
index 0000000..1e81fcf
--- /dev/null
+++ b/src/main/scala/OpaqueTypes2.scala
@@ -0,0 +1,33 @@
+object OpaqueTypes2 extends App {
+  object Access {
+    opaque type Permissions = Int
+    opaque type PermissionChoice = Int
+
+    /** `Permission`'s upper bound is `Permissions & PermissionChoice`.
+      * Thus `Permission` is universally known to be a subtype of `Permissions` and `PermissionChoice`. */
+    opaque type Permission <: Permissions & PermissionChoice = Int
+
+    def (x: Permissions) & (y: Permissions): Permissions = x & y
+    def (x: PermissionChoice) | (y: PermissionChoice): PermissionChoice = x | y
+    def (x: Permissions) is (y: Permissions) = (x & y) == y
+    def (x: Permissions) isOneOf (y: PermissionChoice) = (x & y) != 0
+
+    val NoPermission: Permission = 0
+    val ReadOnly: Permission = 1
+    val WriteOnly: Permission = 2
+    val ReadWrite: Permissions = ReadOnly | WriteOnly
+    val ReadOrWrite: PermissionChoice = ReadOnly | WriteOnly
+  }
+
+  def test: Unit = {
+    import Access._
+
+    case class Item(rights: Permissions)
+
+    val x = Item(ReadOnly)
+    assert( ! x.rights.is(ReadWrite) )
+    assert( x.rights.isOneOf(ReadOrWrite) )
+  }
+
+  test
+}

From 60aac65e2397b536f1e563f06dc6ac639a71a0ef Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 15:47:52 -0500
Subject: [PATCH 41/59] -

---
 src/main/scala/ContextQueries1.scala                       | 4 ++--
 src/main/scala/{ImpliedInstances.scala => Delegates.scala} | 6 +++---
 src/main/scala/Main.scala                                  | 2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)
 rename src/main/scala/{ImpliedInstances.scala => Delegates.scala} (89%)

diff --git a/src/main/scala/ContextQueries1.scala b/src/main/scala/ContextQueries1.scala
index 7242732..7eba54d 100644
--- a/src/main/scala/ContextQueries1.scala
+++ b/src/main/scala/ContextQueries1.scala
@@ -20,10 +20,10 @@ object ContextQueries1 extends App {
   }
 
   object parse {
-    type Parseable[T] = (given ImpliedInstances.StringParser[T]) => Try[T]
+    type Parseable[T] = (given Delegates.StringParser[T]) => Try[T]
 
     def sumStrings(x: String, y: String): Parseable[Int] = {
-      val parser = implicitly[ImpliedInstances.StringParser[Int]]
+      val parser = implicitly[Delegates.StringParser[Int]]
       val tryA = parser.parse(x)
       val tryB = parser.parse(y)
 
diff --git a/src/main/scala/ImpliedInstances.scala b/src/main/scala/Delegates.scala
similarity index 89%
rename from src/main/scala/ImpliedInstances.scala
rename to src/main/scala/Delegates.scala
index 9cdcd8f..89bc7f9 100644
--- a/src/main/scala/ImpliedInstances.scala
+++ b/src/main/scala/Delegates.scala
@@ -1,8 +1,8 @@
 import scala.util.{Success, Try}
 
-/** Implied Instances:
-  * - https://dotty.epfl.ch/docs/reference/contextual/instance-defs.html */
-object ImpliedInstances extends App {
+/** Delegates (Implied Instances):
+  * - https://dotty.epfl.ch/docs/reference/contextual/delegates.html*/
+object Delegates extends App {
   sealed trait StringParser[A] {
     def parse(s: String): Try[A]
   }
diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index 951df2d..c63ee66 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -3,13 +3,13 @@ object Main {
     runExample("Trait Params")(TraitParams.test)
     runExample("Typeclasses")(Typeclasses.test)
     runExample("OpaqueTypes 1")(OpaqueTypes1.test)
+    runExample("Delegates")(Delegates.test)
     runExample("Context Queries 1")(ContextQueries1.test)
     runExample("Intersection Types")(IntersectionTypes.test)
     runExample("Context Queries 2")(ContextQueries2.test)
     runExample("OpaqueTypes 2")(OpaqueTypes2.test)
     runExample("Type Lambda")(TypeLambdas.test)
     runExample("Enum Types")(EnumTypes.test)
-    runExample("Implied Instances")(ImpliedInstances.test)
     runExample("Conversion")(Conversion.test)
     runExample("Multiversal Equality")(MultiversalEquality.test)
     runExample("Named Type Arguments")(NamedTypeArguments.test)

From 849bc0382daf33f3be42b70670ecb31388e421ac Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Tue, 26 Nov 2019 15:52:08 -0500
Subject: [PATCH 42/59] -

---
 src/main/scala/Delegates.scala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/scala/Delegates.scala b/src/main/scala/Delegates.scala
index 89bc7f9..ae5ee84 100644
--- a/src/main/scala/Delegates.scala
+++ b/src/main/scala/Delegates.scala
@@ -1,6 +1,6 @@
 import scala.util.{Success, Try}
 
-/** Delegates (Implied Instances):
+/** Delegates (formerly known as Implied Instances):
   * - https://dotty.epfl.ch/docs/reference/contextual/delegates.html*/
 object Delegates extends App {
   sealed trait StringParser[A] {

From 0ecd5a2c2cd5b95b91fb0e64e3f652d3f0eb40f5 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Wed, 27 Nov 2019 11:47:40 -0500
Subject: [PATCH 43/59] -

---
 src/main/scala/Main.scala      |  1 +
 src/main/scala/SyntaxNew.scala | 28 ++++++++++++++++++++++++++++
 2 files changed, 29 insertions(+)
 create mode 100644 src/main/scala/SyntaxNew.scala

diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index c63ee66..c77be2c 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -1,5 +1,6 @@
 object Main {
   def main(args: Array[String]): Unit = {
+    runExample("New Syntax")(SyntaxNew)
     runExample("Trait Params")(TraitParams.test)
     runExample("Typeclasses")(Typeclasses.test)
     runExample("OpaqueTypes 1")(OpaqueTypes1.test)
diff --git a/src/main/scala/SyntaxNew.scala b/src/main/scala/SyntaxNew.scala
new file mode 100644
index 0000000..f70d55e
--- /dev/null
+++ b/src/main/scala/SyntaxNew.scala
@@ -0,0 +1,28 @@
+@main def SyntaxNew =
+  println("Hello from SyntaxNew")
+
+  def test: Unit =
+    val xs = 0 to 3
+    val xsFiltered = for x <- xs if x > 1 yield x
+    for
+      x <- xsFiltered
+      y <- xsFiltered
+    do println(s"$x * $y = ${x * y}")
+
+  test
+
+/** To run, type `runMain testIf Monday` */
+@main def testIf(day: String) =
+  if day == "Sunday" || day == "Saturday"
+  then println("Today is a weekend, hooray!")
+  else println(s"Today is a workday.")
+
+  /** To run, type `runMain testWhile 3` */
+@main def testWhile(bound: Int) =
+  var x = 0
+
+  def incrementX() =
+    x += 1
+    println(x)
+
+  while x <= bound do incrementX()

From 90332ac9bd9af28866d58e2cb2756adfc9ae03f8 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Wed, 27 Nov 2019 11:48:59 -0500
Subject: [PATCH 44/59] -

---
 src/main/scala/SyntaxNew.scala | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/main/scala/SyntaxNew.scala b/src/main/scala/SyntaxNew.scala
index f70d55e..48dcc7a 100644
--- a/src/main/scala/SyntaxNew.scala
+++ b/src/main/scala/SyntaxNew.scala
@@ -1,3 +1,5 @@
+/** See https://dotty.epfl.ch/blog/2019/08/30/18th-dotty-milestone-release.html */
+
 @main def SyntaxNew =
   println("Hello from SyntaxNew")
 

From e80c0e47a7dac3d93d6161ca2f1fae853695f508 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Wed, 27 Nov 2019 13:27:06 -0500
Subject: [PATCH 45/59] -

---
 README.md                      | 2 +-
 project/build.properties       | 2 ++
 src/main/scala/Delegates.scala | 3 ++-
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index b7acf56..a02223b 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # Example sbt Project that Compiles Using Dotty
 
-I (Mike Slinn) fixed many significant bugs in the [upstream project](https://github.com/lampepfl/dotty-example-project) and added code examples for new major features that were missing.
+I (Mike Slinn, founder of [ScalaCourses.com](https://www.ScalaCourses.com)) fixed many significant bugs in the [upstream project](https://github.com/lampepfl/dotty-example-project) and added code examples for new major features that were missing.
 
 ## Usage
 
diff --git a/project/build.properties b/project/build.properties
index c0bab04..4da2902 100644
--- a/project/build.properties
+++ b/project/build.properties
@@ -1 +1,3 @@
+# Sbt versions older than 1.1.4 are not supported with Dotty.
+# Sbt versions 1.3.3 and 1.3.4 do not work properly with Dotty.
 sbt.version=1.2.8
diff --git a/src/main/scala/Delegates.scala b/src/main/scala/Delegates.scala
index ae5ee84..7b280fa 100644
--- a/src/main/scala/Delegates.scala
+++ b/src/main/scala/Delegates.scala
@@ -1,7 +1,8 @@
 import scala.util.{Success, Try}
 
 /** Delegates (formerly known as Implied Instances):
-  * - https://dotty.epfl.ch/docs/reference/contextual/delegates.html*/
+  * - https://dotty.epfl.ch/docs/reference/contextual/delegates.html
+  * - https://dotty.epfl.ch/docs/reference/contextual/derivation.html*/
 object Delegates extends App {
   sealed trait StringParser[A] {
     def parse(s: String): Try[A]

From 0691fee897622954c6fe41bd89be78af9393e72a Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Wed, 27 Nov 2019 13:31:15 -0500
Subject: [PATCH 46/59] -

---
 src/main/scala/SyntaxNew.scala | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/main/scala/SyntaxNew.scala b/src/main/scala/SyntaxNew.scala
index 48dcc7a..8e4ced0 100644
--- a/src/main/scala/SyntaxNew.scala
+++ b/src/main/scala/SyntaxNew.scala
@@ -1,4 +1,5 @@
-/** See https://dotty.epfl.ch/blog/2019/08/30/18th-dotty-milestone-release.html */
+/** The new and old syntaxes can be mixed freely in one file.
+  * See https://dotty.epfl.ch/blog/2019/08/30/18th-dotty-milestone-release.html */
 
 @main def SyntaxNew =
   println("Hello from SyntaxNew")

From 7e20fff609df423b25a98cb51785b3c991363b26 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Wed, 27 Nov 2019 13:34:27 -0500
Subject: [PATCH 47/59] -

---
 src/main/scala/Main.scala | 52 ++++++++++++++++++---------------------
 1 file changed, 24 insertions(+), 28 deletions(-)

diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index c77be2c..c1882a2 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -1,29 +1,25 @@
-object Main {
-  def main(args: Array[String]): Unit = {
-    runExample("New Syntax")(SyntaxNew)
-    runExample("Trait Params")(TraitParams.test)
-    runExample("Typeclasses")(Typeclasses.test)
-    runExample("OpaqueTypes 1")(OpaqueTypes1.test)
-    runExample("Delegates")(Delegates.test)
-    runExample("Context Queries 1")(ContextQueries1.test)
-    runExample("Intersection Types")(IntersectionTypes.test)
-    runExample("Context Queries 2")(ContextQueries2.test)
-    runExample("OpaqueTypes 2")(OpaqueTypes2.test)
-    runExample("Type Lambda")(TypeLambdas.test)
-    runExample("Enum Types")(EnumTypes.test)
-    runExample("Conversion")(Conversion.test)
-    runExample("Multiversal Equality")(MultiversalEquality.test)
-    runExample("Named Type Arguments")(NamedTypeArguments.test)
-    runExample("Auto Param Tupling")(AutoParamTupling.test)
-    runExample("Structural Types")(StructuralTypes.test)
-    runExample("Pattern Matching")(PatternMatching.test)
-    runExample("Union Types")(UnionTypes.test)
-  }
+@main def Main =
+  runExample("New Syntax")(SyntaxNew)
+  runExample("Trait Params")(TraitParams.test)
+  runExample("Typeclasses")(Typeclasses.test)
+  runExample("OpaqueTypes 1")(OpaqueTypes1.test)
+  runExample("Delegates")(Delegates.test)
+  runExample("Context Queries 1")(ContextQueries1.test)
+  runExample("Intersection Types")(IntersectionTypes.test)
+  runExample("Context Queries 2")(ContextQueries2.test)
+  runExample("OpaqueTypes 2")(OpaqueTypes2.test)
+  runExample("Type Lambda")(TypeLambdas.test)
+  runExample("Enum Types")(EnumTypes.test)
+  runExample("Conversion")(Conversion.test)
+  runExample("Multiversal Equality")(MultiversalEquality.test)
+  runExample("Named Type Arguments")(NamedTypeArguments.test)
+  runExample("Auto Param Tupling")(AutoParamTupling.test)
+  runExample("Structural Types")(StructuralTypes.test)
+  runExample("Pattern Matching")(PatternMatching.test)
+  runExample("Union Types")(UnionTypes.test)
 
-  private def runExample(name: String)
-                        (f: => Unit) = {
-    println(Console.MAGENTA + s"$name example:" + Console.RESET)
-    f
-    println()
-  }
-}
+private def runExample(name: String)
+                      (f: => Unit) =
+  println(Console.MAGENTA + s"$name example:" + Console.RESET)
+  f
+  println()

From a306cccb7b718994ec30f9852308da0b28d5ee61 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Wed, 27 Nov 2019 13:37:46 -0500
Subject: [PATCH 48/59] -

---
 src/main/scala/AutoParamTupling.scala |  8 +++-----
 src/main/scala/ContextQueries1.scala  | 12 ++++--------
 src/main/scala/Main.scala             |  4 ++--
 3 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/src/main/scala/AutoParamTupling.scala b/src/main/scala/AutoParamTupling.scala
index 18825f6..30ec2a3 100644
--- a/src/main/scala/AutoParamTupling.scala
+++ b/src/main/scala/AutoParamTupling.scala
@@ -1,16 +1,14 @@
 /** Automatic Tupling of Function Params: https://dotty.epfl.ch/docs/reference/other-new-features/auto-parameter-tupling.html */
-object AutoParamTupling extends App {
-  def test: Unit = {
+@main def AutoParamTupling =
+  def test: Unit =
     /** In order to get thread safety, you need to put @volatile before lazy vals.
       * https://dotty.epfl.ch/docs/reference/changed-features/lazy-vals.html */
     @volatile lazy val xs: List[String] = List("d", "o", "t", "t", "y")
 
-    /** Current behaviour in Scala 2.12.2 :
+    /** Current behaviour in Scala 2.12 :
       * error: missing parameter type
       * Note: The expected type requires a one-argument function accepting a 2-Tuple.
       * Consider a pattern matching anonymous function, `{ case (s, i) =>  ... }` */
     xs.zipWithIndex.map((s, i) => println(s"$i: $s"))
-  }
 
   test
-}
diff --git a/src/main/scala/ContextQueries1.scala b/src/main/scala/ContextQueries1.scala
index 7eba54d..b60674e 100644
--- a/src/main/scala/ContextQueries1.scala
+++ b/src/main/scala/ContextQueries1.scala
@@ -7,8 +7,8 @@ import scala.util.Try
   * - Their types are implicit function types.
   * - http://dotty.epfl.ch/docs/reference/contextual/implicit-function-types.html,
   * - Old syntax: https://www.scala-lang.org/blog/2016/12/07/implicit-function-types.html */
-object ContextQueries1 extends App {
-  object context {
+@main def ContextQueries1 =
+  object context with
     // type alias Contextual
     type Contextual[T] = (given ExecutionContext) => T
 
@@ -17,9 +17,8 @@ object ContextQueries1 extends App {
 
     def asyncMult(x: Int, y: Int)
                  (given ctx: ExecutionContext): Contextual[Future[Int]] = Future(x * y)
-  }
 
-  object parse {
+  object parse with
     type Parseable[T] = (given Delegates.StringParser[T]) => Try[T]
 
     def sumStrings(x: String, y: String): Parseable[Int] = {
@@ -32,9 +31,8 @@ object ContextQueries1 extends App {
         b <- tryB
       } yield a + b
     }
-  }
 
-  def test: Unit = {
+  def test: Unit =
     import ExecutionContext.Implicits.global
 
     context.asyncSum(3, 4).foreach(x => println("asyncSum: " + x))
@@ -42,7 +40,5 @@ object ContextQueries1 extends App {
 
     println("""parse.sumStrings("3", "4"): """ + parse.sumStrings("3", "4"))
     println("""parse.sumStrings("3", "a"): """ + parse.sumStrings("3", "a"))
-  }
 
   test
-}
diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index c1882a2..be3c7fa 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -4,7 +4,7 @@
   runExample("Typeclasses")(Typeclasses.test)
   runExample("OpaqueTypes 1")(OpaqueTypes1.test)
   runExample("Delegates")(Delegates.test)
-  runExample("Context Queries 1")(ContextQueries1.test)
+  runExample("Context Queries 1")(ContextQueries1)
   runExample("Intersection Types")(IntersectionTypes.test)
   runExample("Context Queries 2")(ContextQueries2.test)
   runExample("OpaqueTypes 2")(OpaqueTypes2.test)
@@ -13,7 +13,7 @@
   runExample("Conversion")(Conversion.test)
   runExample("Multiversal Equality")(MultiversalEquality.test)
   runExample("Named Type Arguments")(NamedTypeArguments.test)
-  runExample("Auto Param Tupling")(AutoParamTupling.test)
+  runExample("Automatic Functional Parameter Tupling")(AutoParamTupling)
   runExample("Structural Types")(StructuralTypes.test)
   runExample("Pattern Matching")(PatternMatching.test)
   runExample("Union Types")(UnionTypes.test)

From ad71ce3fca24e8ef879c4e9451e4859dd185b2c3 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Wed, 27 Nov 2019 13:48:06 -0500
Subject: [PATCH 49/59] -

---
 src/main/scala/ContextQueries2.scala | 14 ++++++--------
 src/main/scala/Main.scala            |  2 +-
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/src/main/scala/ContextQueries2.scala b/src/main/scala/ContextQueries2.scala
index d39e671..fd3fe8e 100644
--- a/src/main/scala/ContextQueries2.scala
+++ b/src/main/scala/ContextQueries2.scala
@@ -1,7 +1,7 @@
 /** This example combines opaque aliases, implicit function types, and extension methods to provide
   * a zero-overhead abstraction at runtime.
   * See http://dotty.epfl.ch/docs/reference/contextual/implicit-function-types.html#example-postconditions */
-object PostConditions {
+object PostConditions
   opaque type WrappedResult[T] = T
 
   def result[T](given r: WrappedResult[T]): T = r
@@ -11,17 +11,15 @@ object PostConditions {
     * The given `WrappedResult` instance is passed to the result method.
     * `WrappedResult` is an opaque type alias, so its values need not be boxed or unboxed.
     * Because `ensuring` is added as an extension method, its argument also does not need boxing. */
-  def [T](x: T) ensuring(condition: (given WrappedResult[T]) => Boolean): T = {
+  def [T](x: T) ensuring(condition: (given WrappedResult[T]) => Boolean): T =
     assert(condition(given x))
     x
-  }
-}
 
-object ContextQueries2 extends App {
+@main def ContextQueries2 =
   import PostConditions.{ensuring, result}
 
-  def test: Unit = {
+  def test: Unit =
     val s = List(1, 2, 3).sum.ensuring(result == 6)
     println("Yes, the list sums to 6.")
-  }
-}
+
+  test
diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index be3c7fa..64af6f5 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -6,7 +6,7 @@
   runExample("Delegates")(Delegates.test)
   runExample("Context Queries 1")(ContextQueries1)
   runExample("Intersection Types")(IntersectionTypes.test)
-  runExample("Context Queries 2")(ContextQueries2.test)
+  runExample("Context Queries 2")(ContextQueries2)
   runExample("OpaqueTypes 2")(OpaqueTypes2.test)
   runExample("Type Lambda")(TypeLambdas.test)
   runExample("Enum Types")(EnumTypes.test)

From 0c21c60568d42091794637f00a34815c9227469c Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Wed, 27 Nov 2019 13:50:31 -0500
Subject: [PATCH 50/59] -

---
 src/main/scala/Delegates.scala | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/src/main/scala/Delegates.scala b/src/main/scala/Delegates.scala
index 7b280fa..4403f97 100644
--- a/src/main/scala/Delegates.scala
+++ b/src/main/scala/Delegates.scala
@@ -3,12 +3,11 @@ import scala.util.{Success, Try}
 /** Delegates (formerly known as Implied Instances):
   * - https://dotty.epfl.ch/docs/reference/contextual/delegates.html
   * - https://dotty.epfl.ch/docs/reference/contextual/derivation.html*/
-object Delegates extends App {
-  sealed trait StringParser[A] {
+object Delegates with
+  sealed trait StringParser[A]
     def parse(s: String): Try[A]
-  }
 
-  object StringParser {
+  object StringParser with
     def apply[A](given parser: StringParser[A]): StringParser[A] = parser
 
     private def baseParser[A](f: String ⇒ Try[A]): StringParser[A] =
@@ -21,20 +20,16 @@ object Delegates extends App {
 
     given optionParser[A](given parser: => StringParser[A]): StringParser[Option[A]] =
       new StringParser[Option[A]] {
-        override def parse(s: String): Try[Option[A]] = s match {
+        override def parse(s: String): Try[Option[A]] = s match
           case "" ⇒ Success(None) // implicit parser not used.
           case str ⇒ parser.parse(str).map(Some(_)) // implicit parser is evaluated here
-        }
       }
-  }
 
-  def test: Unit = {
+  def test: Unit =
     val spoi = implicitly[StringParser[Option[Int]]]
     println(spoi.parse("21"))
     println(spoi.parse(""))
     println(spoi.parse("21a"))
     println(StringParser.optionParser[Int].parse("42"))
-  }
 
   test
-}

From 406166a6c7b9ed7fe8f4146262e1b19ba9f75569 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Wed, 27 Nov 2019 13:54:08 -0500
Subject: [PATCH 51/59] -

---
 src/main/scala/EnumTypes.scala           | 15 +++++----------
 src/main/scala/Main.scala                |  6 +++---
 src/main/scala/MultiversalEquality.scala |  7 ++-----
 src/main/scala/NamedTypeArguments.scala  | 12 ++++--------
 4 files changed, 14 insertions(+), 26 deletions(-)

diff --git a/src/main/scala/EnumTypes.scala b/src/main/scala/EnumTypes.scala
index 139e8e0..9b5ceae 100644
--- a/src/main/scala/EnumTypes.scala
+++ b/src/main/scala/EnumTypes.scala
@@ -2,14 +2,13 @@
   * * Interoperate with Java enums
   * * Support Algebraic Data Types (ADTs) because they accept type parameters, and can be Generalized ADTs (GADTs).
   * See http://dotty.epfl.ch/docs/reference/enums/adts.html */
-object EnumTypes extends App {
-  enum ListEnum[+A] {
+@main def EnumTypes =
+  enum ListEnum[+A]
     case Cons(h: A, t: ListEnum[A])
     case Empty
-  }
 
   /** This looks a lot like the [old Java enum example](https://docs.oracle.com/javase/tutorial/java/javaOO/enum.html) */
-  enum Planet(mass: Double, radius: Double) {
+  enum Planet(mass: Double, radius: Double) with
     private final val G = 6.67300E-11
 
     def surfaceGravity = G * mass / (radius * radius)
@@ -24,23 +23,19 @@ object EnumTypes extends App {
     case Saturn  extends Planet(5.688e+26, 6.0268e7)
     case Uranus  extends Planet(8.686e+25, 2.5559e7)
     case Neptune extends Planet(1.024e+26, 2.4746e7)
-  }
 
-  def test: Unit = {
+  def test: Unit =
     val emptyList = ListEnum.Empty
     val list = ListEnum.Cons(1, ListEnum.Cons(2, ListEnum.Cons(3, ListEnum.Empty)))
     println(emptyList)
     println(s"$list\n")
 
-    def calculateEarthWeightOnPlanets(earthWeight: Double): Unit = {
+    def calculateEarthWeightOnPlanets(earthWeight: Double): Unit =
       val mass = earthWeight/Planet.Earth.surfaceGravity
       for (p <- Planet.values)
         println(s"Your weight on $p is ${p.surfaceWeight(mass)}")
       ()
-    }
 
     calculateEarthWeightOnPlanets(80)
-  }
 
   test
-}
diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index 64af6f5..8b53e51 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -9,10 +9,10 @@
   runExample("Context Queries 2")(ContextQueries2)
   runExample("OpaqueTypes 2")(OpaqueTypes2.test)
   runExample("Type Lambda")(TypeLambdas.test)
-  runExample("Enum Types")(EnumTypes.test)
+  runExample("Enum Types")(EnumTypes)
   runExample("Conversion")(Conversion.test)
-  runExample("Multiversal Equality")(MultiversalEquality.test)
-  runExample("Named Type Arguments")(NamedTypeArguments.test)
+  runExample("Multiversal Equality")(MultiversalEquality)
+  runExample("Named Type Arguments")(NamedTypeArguments)
   runExample("Automatic Functional Parameter Tupling")(AutoParamTupling)
   runExample("Structural Types")(StructuralTypes.test)
   runExample("Pattern Matching")(PatternMatching.test)
diff --git a/src/main/scala/MultiversalEquality.scala b/src/main/scala/MultiversalEquality.scala
index df317d4..056e50e 100644
--- a/src/main/scala/MultiversalEquality.scala
+++ b/src/main/scala/MultiversalEquality.scala
@@ -4,9 +4,8 @@ import scala.language.strictEquality
   * Multiversal Equality: https://dotty.epfl.ch/docs/reference/contextual/multiversal-equality.html
   * scala.Eq definition: https://github.com/lampepfl/dotty/blob/master/library/src/scala/Eql.scala
   */
-  object MultiversalEquality extends App {
-
-  def test: Unit = {
+@main def MultiversalEquality =
+  def test: Unit =
     // Values of types Int and String cannot be compared with == or !=,
     // unless we add the derived delegate instance like:
     given Eql[Int, String] = Eql.derived
@@ -37,7 +36,5 @@ import scala.language.strictEquality
 
     println("a != b: " + (a != b))
     println("b == a: " + (b == a))
-  }
 
   test
-}
diff --git a/src/main/scala/NamedTypeArguments.scala b/src/main/scala/NamedTypeArguments.scala
index bb7402f..4aa20e1 100644
--- a/src/main/scala/NamedTypeArguments.scala
+++ b/src/main/scala/NamedTypeArguments.scala
@@ -1,16 +1,14 @@
 /** Named Type Arguments: https://dotty.epfl.ch/docs/reference/other-new-features/named-typeargs.html */
-object NamedTypeArguments extends App {
-  trait Functor[F[_]] {
+@main def NamedTypeArguments =
+  trait Functor[F[_]]
     def map[A, B](fa: F[A])
                  (f: A => B): F[B]
-  }
 
-  implicit object listFunctor extends Functor[List] {
+  implicit object listFunctor extends Functor[List] with
     override def map[A, B](fa: List[A])
                           (f: A => B): List[B] = fa.map(f)
-  }
 
-  def test: Unit = {
+  def test: Unit =
     def fmap[F[_], A, B](fa: F[A])
                         (f: A => B)
                         (implicit F: Functor[F]): F[B] = F.map(fa)(f)
@@ -24,7 +22,5 @@ object NamedTypeArguments extends App {
     val compile: List[String] = fmap[F = List, B = String](List(1,2,3))(i => (i + 1).toString)
 
     println(compile)
-  }
 
   test
-}

From c183838546ed6908a2d1d418d96aa5a94a633366 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Wed, 27 Nov 2019 13:56:26 -0500
Subject: [PATCH 52/59] -

---
 src/main/scala/Main.scala         |  2 +-
 src/main/scala/OpaqueTypes1.scala | 15 +++++----------
 2 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index 8b53e51..29c4840 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -2,7 +2,7 @@
   runExample("New Syntax")(SyntaxNew)
   runExample("Trait Params")(TraitParams.test)
   runExample("Typeclasses")(Typeclasses.test)
-  runExample("OpaqueTypes 1")(OpaqueTypes1.test)
+  runExample("OpaqueTypes 1")(OpaqueTypes1)
   runExample("Delegates")(Delegates.test)
   runExample("Context Queries 1")(ContextQueries1)
   runExample("Intersection Types")(IntersectionTypes.test)
diff --git a/src/main/scala/OpaqueTypes1.scala b/src/main/scala/OpaqueTypes1.scala
index 6ec2bcc..dd65488 100644
--- a/src/main/scala/OpaqueTypes1.scala
+++ b/src/main/scala/OpaqueTypes1.scala
@@ -1,32 +1,27 @@
 /** Opaque types aliases provide type abstraction without *any* runtime overhead.
   * They replace Scala 2 value types.
   * See https://dotty.epfl.ch/docs/reference/other-new-features/opaques.html */
-object OpaqueTypes1 extends App {
-  object Logarithms {
+@main def OpaqueTypes1 =
+  object Logarithms with
     opaque type Logarithm = Double
 
-    object Logarithm {
+    object Logarithm with
       // These are the ways to lift to the logarithm type
       def apply(d: Double): Logarithm = math.log(d)
 
       def safe(d: Double): Option[Logarithm] =
         if (d > 0.0) Some(math.log(d)) else None
-    }
 
     // Extension methods define opaque types' public APIs
-    given logarithmOps: {
+    given logarithmOps: with
       def (x: Logarithm) toDouble: Double = math.exp(x)
       def (x: Logarithm) + (y: Logarithm): Logarithm = Logarithm(math.exp(x) + math.exp(y))
       def (x: Logarithm) * (y: Logarithm): Logarithm = Logarithm(x + y)
-    }
-  }
 
-  def test: Unit = {
+  def test: Unit =
     import Logarithms._
 
     println("Logarithm(1.0) * Logarithm(2.0): " + (Logarithm(1.0) * Logarithm(2.0)))
     println("Logarithm(1.0) + Logarithm(2.0): " + (Logarithm(1.0) + Logarithm(2.0)))
-  }
 
   test
-}

From cb20d0d54aa316aee89f3ed31849d9791fc2e93c Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Wed, 27 Nov 2019 13:59:33 -0500
Subject: [PATCH 53/59] -

---
 src/main/scala/Main.scala            |  4 +--
 src/main/scala/OpaqueTypes2.scala    |  9 ++----
 src/main/scala/PatternMatching.scala | 46 +++++++++-------------------
 3 files changed, 20 insertions(+), 39 deletions(-)

diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index 29c4840..28f24d8 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -7,7 +7,7 @@
   runExample("Context Queries 1")(ContextQueries1)
   runExample("Intersection Types")(IntersectionTypes.test)
   runExample("Context Queries 2")(ContextQueries2)
-  runExample("OpaqueTypes 2")(OpaqueTypes2.test)
+  runExample("OpaqueTypes 2")(OpaqueTypes2)
   runExample("Type Lambda")(TypeLambdas.test)
   runExample("Enum Types")(EnumTypes)
   runExample("Conversion")(Conversion.test)
@@ -15,7 +15,7 @@
   runExample("Named Type Arguments")(NamedTypeArguments)
   runExample("Automatic Functional Parameter Tupling")(AutoParamTupling)
   runExample("Structural Types")(StructuralTypes.test)
-  runExample("Pattern Matching")(PatternMatching.test)
+  runExample("Pattern Matching")(PatternMatching)
   runExample("Union Types")(UnionTypes.test)
 
 private def runExample(name: String)
diff --git a/src/main/scala/OpaqueTypes2.scala b/src/main/scala/OpaqueTypes2.scala
index 1e81fcf..fc120b5 100644
--- a/src/main/scala/OpaqueTypes2.scala
+++ b/src/main/scala/OpaqueTypes2.scala
@@ -1,5 +1,5 @@
-object OpaqueTypes2 extends App {
-  object Access {
+@main def OpaqueTypes2 =
+  object Access with
     opaque type Permissions = Int
     opaque type PermissionChoice = Int
 
@@ -17,9 +17,8 @@ object OpaqueTypes2 extends App {
     val WriteOnly: Permission = 2
     val ReadWrite: Permissions = ReadOnly | WriteOnly
     val ReadOrWrite: PermissionChoice = ReadOnly | WriteOnly
-  }
 
-  def test: Unit = {
+  def test: Unit =
     import Access._
 
     case class Item(rights: Permissions)
@@ -27,7 +26,5 @@ object OpaqueTypes2 extends App {
     val x = Item(ReadOnly)
     assert( ! x.rights.is(ReadWrite) )
     assert( x.rights.isOneOf(ReadOrWrite) )
-  }
 
   test
-}
diff --git a/src/main/scala/PatternMatching.scala b/src/main/scala/PatternMatching.scala
index f126eb2..df8fd2c 100644
--- a/src/main/scala/PatternMatching.scala
+++ b/src/main/scala/PatternMatching.scala
@@ -1,13 +1,11 @@
 /** Pattern Matching: https://dotty.epfl.ch/docs/reference/changed-features/pattern-matching.html */
-object PatternMatching extends App {
-  object booleanPattern {
-    object Even {
+@main def PatternMatching =
+  object booleanPattern with
+    object Even with
       def unapply(s: String): Boolean = s.length % 2 == 0
-    }
-  }
 
-  object productPattern {
-    class Person(name: String, age: Int) extends Product {
+  object productPattern with
+    class Person(name: String, age: Int) extends Product
       // if we not define that, it will give compile error.
       // we change the order
       def _1 = age
@@ -17,35 +15,25 @@ object PatternMatching extends App {
       def canEqual(that: Any): Boolean = ???
       def productArity: Int = ???
       def productElement(n: Int): Any = ???
-    }
 
-    object Person {
+    object Person with
       def unapply(a: (String, Int)): Person = new Person(a._1, a._2)
-    }
-  }
 
-  object seqPattern {
+  object seqPattern with
     // adapted from http://danielwestheide.com/blog/2012/11/28/the-neophytes-guide-to-scala-part-2-extracting-sequences.html
-    object Names {
-      def unapplySeq(name: String): Option[Seq[String]] = {
+    object Names with
+      def unapplySeq(name: String): Option[Seq[String]] =
         val names = name.trim.split(" ")
         if (names.size < 2) None
         else Some(names.last :: names.head :: names.drop(1).dropRight(1).toList)
-      }
-    }
-
-  }
 
-  object namePattern {
-    class Name(val name: String) {
+  object namePattern with
+    class Name(val name: String)
       def get: String = name
       def isEmpty = name.isEmpty
-    }
 
-    object Name {
+    object Name with
       def unapply(s: String): Name = new Name(s)
-    }
-  }
 
   def test: Unit = {
     import booleanPattern._
@@ -66,27 +54,23 @@ object PatternMatching extends App {
     println(containsConsecutive(List(1, 2, 3, 3, 5)))
 
     import productPattern._
-    ("john", 42) match {
+    ("john", 42) match
       case Person(n, a) => println(s"name: $n, age: $a")
-    }
 
     import seqPattern._
 
-    def greet(fullName: String) = fullName match {
+    def greet(fullName: String) = fullName match
       case Names(lastName, firstName, _: _*) => "Good morning, " + firstName + " " + lastName + "!"
       case _ => "Welcome! Please make sure to fill in your name!"
-    }
 
     println(greet("Alan Turing"))
     println(greet("john"))
     println(greet("Wolfgang Amadeus Mozart"))
 
     import namePattern._
-    "alice" match {
+    "alice" match
       case Name(n) => println(s"name is $n")
       case _ => println("empty name")
-    }
   }
 
   test
-}

From 5e33baf909e3f4ff38e26d0bbc31ab3496836a52 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Wed, 27 Nov 2019 14:01:58 -0500
Subject: [PATCH 54/59] -

---
 src/main/scala/Main.scala            |  4 ++--
 src/main/scala/StructuralTypes.scala | 12 ++++--------
 src/main/scala/TraitParams.scala     | 10 ++++------
 3 files changed, 10 insertions(+), 16 deletions(-)

diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index 28f24d8..75c136b 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -1,6 +1,6 @@
 @main def Main =
   runExample("New Syntax")(SyntaxNew)
-  runExample("Trait Params")(TraitParams.test)
+  runExample("Trait Params")(TraitParams)
   runExample("Typeclasses")(Typeclasses.test)
   runExample("OpaqueTypes 1")(OpaqueTypes1)
   runExample("Delegates")(Delegates.test)
@@ -14,7 +14,7 @@
   runExample("Multiversal Equality")(MultiversalEquality)
   runExample("Named Type Arguments")(NamedTypeArguments)
   runExample("Automatic Functional Parameter Tupling")(AutoParamTupling)
-  runExample("Structural Types")(StructuralTypes.test)
+  runExample("Structural Types")(StructuralTypes)
   runExample("Pattern Matching")(PatternMatching)
   runExample("Union Types")(UnionTypes.test)
 
diff --git a/src/main/scala/StructuralTypes.scala b/src/main/scala/StructuralTypes.scala
index 2f46280..8f6c8bd 100644
--- a/src/main/scala/StructuralTypes.scala
+++ b/src/main/scala/StructuralTypes.scala
@@ -1,25 +1,21 @@
 /** Structural Types: https://dotty.epfl.ch/docs/reference/changed-features/structural-types.html */
-object StructuralTypes extends App {
-  case class Record(elems: (String, Any)*) extends Selectable {
+@main def StructuralTypes =
+  case class Record(elems: (String, Any)*) extends Selectable
     def selectDynamic(name: String): Any = elems.find(_._1 == name).get._2
-  }
 
-  type Person = Record {
+  type Person = Record with
     val name: String
     val age: Int
-  }
 
   val person = Record("name" -> "Emma", "age" -> 42, "salary" -> 320L).asInstanceOf[Person]
 
   val invalidPerson = Record("name" -> "John", "salary" -> 42).asInstanceOf[Person]
 
-  def test: Unit = {
+  def test: Unit =
     println(person.name)
     println(person.age)
     println(invalidPerson.name)
     // age field is java.util.NoSuchElementException: None.get
     //println(invalidPerson.age)
-  }
 
   test
-}
diff --git a/src/main/scala/TraitParams.scala b/src/main/scala/TraitParams.scala
index 6d17c9e..06c36e3 100644
--- a/src/main/scala/TraitParams.scala
+++ b/src/main/scala/TraitParams.scala
@@ -1,23 +1,21 @@
 /** Trait Parameters: https://dotty.epfl.ch/docs/reference/other-new-features/trait-parameters.html */
-object TraitParams extends App {
+@main def TraitParams =
   trait Base(val msg: String)
 
   class A extends Base("Hello")
   class B extends Base("Dotty")
 
   /** @param msgs varargs union type (sequence of A or B) */
-  private def printMessages1(msgs: (A | B)*): Unit = println(msgs.map(_.msg).mkString(" ") + "!")
+  def printMessages1(msgs: (A | B)*): Unit = println(msgs.map(_.msg).mkString(" ") + "!")
 
 
   case class C(override val msg: String) extends Base(msg)
   case class D(override val msg: String) extends Base(msg)
 
-  private def printMessages2(msgs: (C | D)*): Unit = println(msgs.map(_.msg).mkString(" ") + "!")
+  def printMessages2(msgs: (C | D)*): Unit = println(msgs.map(_.msg).mkString(" ") + "!")
 
-  def test: Unit = {
+  def test: Unit =
     printMessages1(new A, new B)
     printMessages2(C("Goodbye"), D("cruel world"))
-  }
 
   test
-}

From de3ab8a1da41c0bed5db979146dddd87bb5fc128 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Wed, 27 Nov 2019 14:08:07 -0500
Subject: [PATCH 55/59] -

---
 src/main/scala/Conversion.scala  | 27 ++++++++-------------------
 src/main/scala/Main.scala        | 10 +++++-----
 src/main/scala/TypeLambdas.scala |  6 ++----
 src/main/scala/Typeclasses.scala |  3 +--
 src/main/scala/UnionTypes.scala  | 14 +++++---------
 5 files changed, 21 insertions(+), 39 deletions(-)

diff --git a/src/main/scala/Conversion.scala b/src/main/scala/Conversion.scala
index ec65bca..686ec0e 100644
--- a/src/main/scala/Conversion.scala
+++ b/src/main/scala/Conversion.scala
@@ -1,35 +1,24 @@
 import scala.language.implicitConversions
 
-/** Conversions: http://dotty.epfl.ch/docs/reference/contextual/conversions.html */
-object Conversion extends App {
-  case class IntWrapper(a: Int) extends AnyVal
-  case class DoubleWrapper(b: Double) extends AnyVal
+case class IntWrapper(a: Int) extends AnyVal
+case class DoubleWrapper(b: Double) extends AnyVal
 
+/** Conversions: http://dotty.epfl.ch/docs/reference/contextual/conversions.html */
+@main def Conversion =
   def convert[T, U](t: T)
                    (given converter: Conversion[T, U]): U = converter(t)
 
   given IntWrapperToDoubleWrapper: Conversion[IntWrapper, DoubleWrapper] =
-    new Conversion[IntWrapper, DoubleWrapper] {
+    new Conversion[IntWrapper, DoubleWrapper] with
       override def apply(i: IntWrapper): DoubleWrapper = new DoubleWrapper(i.a.toDouble)
-    }
-
-  def useConversion(given f: Conversion[IntWrapper, DoubleWrapper]) = {
+    
+  def useConversion(given f: Conversion[IntWrapper, DoubleWrapper]) =
     val y: IntWrapper = new IntWrapper(4)
     val x: DoubleWrapper = y
     x
-  }
-
-  /* Not working anymore.
-    def useConversion(implicit f: A => B) = {
-      val y: A = ...
-      val x: B = a    // error under Dotty
-    }
-   */
 
-  def test: Unit = {
+  def test: Unit =
     println(useConversion)
     println(convert(new IntWrapper(42)))
-  }
 
   test
-}
diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index 75c136b..7715c6c 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -1,22 +1,22 @@
 @main def Main =
   runExample("New Syntax")(SyntaxNew)
   runExample("Trait Params")(TraitParams)
-  runExample("Typeclasses")(Typeclasses.test)
+  runExample("Typeclasses")(Typeclasses)
   runExample("OpaqueTypes 1")(OpaqueTypes1)
   runExample("Delegates")(Delegates.test)
   runExample("Context Queries 1")(ContextQueries1)
-  runExample("Intersection Types")(IntersectionTypes.test)
+  runExample("Intersection Types")(IntersectionTypes)
   runExample("Context Queries 2")(ContextQueries2)
   runExample("OpaqueTypes 2")(OpaqueTypes2)
-  runExample("Type Lambda")(TypeLambdas.test)
+  runExample("Type Lambda")(TypeLambdas)
   runExample("Enum Types")(EnumTypes)
-  runExample("Conversion")(Conversion.test)
+  runExample("Conversion")(Conversion)
   runExample("Multiversal Equality")(MultiversalEquality)
   runExample("Named Type Arguments")(NamedTypeArguments)
   runExample("Automatic Functional Parameter Tupling")(AutoParamTupling)
   runExample("Structural Types")(StructuralTypes)
   runExample("Pattern Matching")(PatternMatching)
-  runExample("Union Types")(UnionTypes.test)
+  runExample("Union Types")(UnionTypes)
 
 private def runExample(name: String)
                       (f: => Unit) =
diff --git a/src/main/scala/TypeLambdas.scala b/src/main/scala/TypeLambdas.scala
index 32dd5c8..3de219f 100644
--- a/src/main/scala/TypeLambdas.scala
+++ b/src/main/scala/TypeLambdas.scala
@@ -1,16 +1,14 @@
 /** Type Lambdas: https://dotty.epfl.ch/docs/reference/new-types/type-lambdas.html */
-object TypeLambdas extends App {
+@main def TypeLambdas =
   type T[+X, Y] = Map[Y, X]
 
   type Tuple = [X] =>> (X, X)
 
-  def test: Unit = {
+  def test: Unit =
     val m: T[String, Int] = Map(1 -> "1")
     println(m)
 
     val tuple: Tuple[String] = ("a", "b")
     println(tuple)
-  }
 
   test
-}
diff --git a/src/main/scala/Typeclasses.scala b/src/main/scala/Typeclasses.scala
index 10dd307..307da9c 100644
--- a/src/main/scala/Typeclasses.scala
+++ b/src/main/scala/Typeclasses.scala
@@ -4,7 +4,7 @@
   * * Better error messages than generated from implicits
   * * Implicit conversions will go away
   * See https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/delegates */
-object Typeclasses extends App {
+@main def Typeclasses =
   trait SemiGroup[T] with
     def (x: T) combine (y: T): T
 
@@ -21,4 +21,3 @@ object Typeclasses extends App {
   def test: Unit = println("""sum("a", "b", "c"): """ + sum(List("a", "b", "c")))
 
   test
-}
diff --git a/src/main/scala/UnionTypes.scala b/src/main/scala/UnionTypes.scala
index 52beebf..1e8c458 100644
--- a/src/main/scala/UnionTypes.scala
+++ b/src/main/scala/UnionTypes.scala
@@ -4,7 +4,7 @@
   * * Works with singleton types
   * * Good for Scala/JavaScript interoperability
   * https://dotty.epfl.ch/docs/reference/new-types/union-types.html */
-object UnionTypes extends App {
+@main def UnionTypes =
   sealed trait Division
   final case class DivisionByZero(msg: String) extends Division
   final case class Success(double: Double) extends Division
@@ -14,19 +14,17 @@ object UnionTypes extends App {
 
   sealed trait List[+A]
   final case class Cons[+A](h: A, t: List[A]) extends List[A]
-  final class Empty extends List[Nothing] {
+  final class Empty extends List[Nothing]
     override def toString: String = "Empty"
-  }
 
-  private def safeDivide(a: Double, b: Double): DivisionResult =
+  def safeDivide(a: Double, b: Double): DivisionResult =
     if (b == 0) DivisionByZero("DivisionByZeroException") else Success(a / b)
 
-  private def either(division: Division) = division match {
+  def either(division: Division) = division match 
     case DivisionByZero(m) => Left(m)
     case Success(d) => Right(d)
-  }
 
-  def test: Unit = {
+  def test: Unit =
     val divisionResultSuccess: DivisionResult = safeDivide(4, 2)
 
     // Commutative
@@ -43,7 +41,5 @@ object UnionTypes extends App {
 
     val emptyList: Empty | Cons[Any] = Empty()
     println("emptyList: " + emptyList)
-  }
 
   test
-}

From 5cb4e2f1c4ab4ce7800ab5ed2f6b9a149cc59a99 Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Wed, 27 Nov 2019 14:09:05 -0500
Subject: [PATCH 56/59] -

---
 src/main/scala/Main.scala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index 7715c6c..baa3839 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -3,7 +3,7 @@
   runExample("Trait Params")(TraitParams)
   runExample("Typeclasses")(Typeclasses)
   runExample("OpaqueTypes 1")(OpaqueTypes1)
-  runExample("Delegates")(Delegates.test)
+  runExample("Delegates")(Delegates)
   runExample("Context Queries 1")(ContextQueries1)
   runExample("Intersection Types")(IntersectionTypes)
   runExample("Context Queries 2")(ContextQueries2)

From d14cc128b29c16d1ecad6658e2ed399cd495488d Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Wed, 27 Nov 2019 14:28:46 -0500
Subject: [PATCH 57/59] -

---
 src/main/scala/Main.scala        | 2 +-
 src/main/scala/Typeclasses.scala | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/main/scala/Main.scala b/src/main/scala/Main.scala
index baa3839..34a17c4 100644
--- a/src/main/scala/Main.scala
+++ b/src/main/scala/Main.scala
@@ -8,7 +8,7 @@
   runExample("Intersection Types")(IntersectionTypes)
   runExample("Context Queries 2")(ContextQueries2)
   runExample("OpaqueTypes 2")(OpaqueTypes2)
-  runExample("Type Lambda")(TypeLambdas)
+  runExample("Type Lambdas")(TypeLambdas)
   runExample("Enum Types")(EnumTypes)
   runExample("Conversion")(Conversion)
   runExample("Multiversal Equality")(MultiversalEquality)
diff --git a/src/main/scala/Typeclasses.scala b/src/main/scala/Typeclasses.scala
index 307da9c..fd0c876 100644
--- a/src/main/scala/Typeclasses.scala
+++ b/src/main/scala/Typeclasses.scala
@@ -18,6 +18,7 @@
   def sum[T: Monoid](xs: List[T]): T =
     xs.foldLeft(summon[Monoid[T]].unit)(_.combine(_))
 
-  def test: Unit = println("""sum("a", "b", "c"): """ + sum(List("a", "b", "c")))
+  def test: Unit =
+    println("""sum("a", "b", "c"): """ + sum(List("a", "b", "c")))
 
   test

From 641bfa6f2315f70d5ba22b775f0d496ca913d27e Mon Sep 17 00:00:00 2001
From: Mike Slinn <mslinn@micronauticsresearch.com>
Date: Thu, 28 Nov 2019 10:20:01 -0500
Subject: [PATCH 58/59] -

---
 src/main/scala/ContextQueries1.scala   |  3 ++-
 src/main/scala/IntersectionTypes.scala | 20 +++++++-------------
 2 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/src/main/scala/ContextQueries1.scala b/src/main/scala/ContextQueries1.scala
index b60674e..049f33a 100644
--- a/src/main/scala/ContextQueries1.scala
+++ b/src/main/scala/ContextQueries1.scala
@@ -16,7 +16,8 @@ import scala.util.Try
     def asyncSum(x: Int, y: Int): Contextual[Future[Int]] = Future(x + y)
 
     def asyncMult(x: Int, y: Int)
-                 (given ctx: ExecutionContext): Contextual[Future[Int]] = Future(x * y)
+                 (given ctx: ExecutionContext): Contextual[Future[Int]] =
+                   Future(x * y)
 
   object parse with
     type Parseable[T] = (given Delegates.StringParser[T]) => Try[T]
diff --git a/src/main/scala/IntersectionTypes.scala b/src/main/scala/IntersectionTypes.scala
index ceae350..6fd10d2 100644
--- a/src/main/scala/IntersectionTypes.scala
+++ b/src/main/scala/IntersectionTypes.scala
@@ -1,34 +1,28 @@
 /**
   * Intersection Types: https://dotty.epfl.ch/docs/reference/new-types/intersection-types.html
   */
-object IntersectionTypes extends App {
-  sealed trait X {
+@main def IntersectionTypes =
+  sealed trait X
     def x: Double
     def tpe: X
-  }
 
-  sealed trait Y {
+  sealed trait Y
     def y: Double
     def tpe: Y
-  }
 
   // The compiler treats P and PP as equivalent and interchangeable types
   type P = Y & X
   type PP = X & Y
 
-  final case class Point(x: Double, y: Double) extends X with Y {
-    override def tpe: X & Y = ???
-  }
+  final case class Point(x: Double, y: Double) extends X with Y
+    override def tpe: P = ???
 
-  def test: Unit = {
-    def euclideanDistance(p1: P, p2: P) = {
+  def test: Unit =
+    def euclideanDistance(p1: P, p2: P) =
       Math.sqrt(Math.pow(p2.y - p1.y, 2) + Math.pow(p2.x - p1.x, 2))
-    }
 
     val p1: P = Point(3, 4)
     val p2: PP = Point(6, 8)
     println(euclideanDistance(p1, p2))
-  }
 
   test
-}

From 5b27ab71ace8bf83b999630d3cf2d3c1dc27ae63 Mon Sep 17 00:00:00 2001
From: Scala Steward <me@scala-steward.org>
Date: Wed, 2 Dec 2020 12:57:45 +0100
Subject: [PATCH 59/59] Update sbt to 1.4.4

---
 project/build.properties | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/project/build.properties b/project/build.properties
index 4da2902..cb23649 100644
--- a/project/build.properties
+++ b/project/build.properties
@@ -1,3 +1,3 @@
 # Sbt versions older than 1.1.4 are not supported with Dotty.
 # Sbt versions 1.3.3 and 1.3.4 do not work properly with Dotty.
-sbt.version=1.2.8
+sbt.version=1.4.4