Add more snippets/Remove unused code in root folder (#120)

Author: eloots

code-snippets/build.sbt

@@ -3,6 +3,7 @@ Global / onChangedBuildSource := ReloadOnSourceChanges
 lazy val `scala-3-snippets` = project
   .in(file("."))
   .settings(ThisBuild / scalaVersion := "3.3.0")
+  .settings(ThisBuild / scalacOptions ++= Seq("-source", "3.3-migration"))
   .settings(
     name := "dotty-simple",
     version := "0.1.0",
@@ -13,7 +14,8 @@ lazy val `scala-3-snippets` = project
     `intersection-and-union-types`,
     `enumerations`,
     `export-clause`,
-    `top-level-definitions`)
+    `top-level-definitions`,
+    `opaque-type-aliases`)
 
 lazy val `new-control-structure-syntax` = project.in(file("new-control-structure-syntax"))
 
@@ -24,6 +26,8 @@ lazy val `enumerations` = project.in(file("enumerations"))
 lazy val `export-clause` = project.in(file("export-clause"))
 
 lazy val `intersection-and-union-types` =
-  project.in(file("intersection-and-union-types")).settings(scalacOptions ++= Seq("-source", "future-migration"))
+  project.in(file("intersection-and-union-types"))
 
 lazy val `top-level-definitions` = project.in(file("top-level-definitions"))
+
+lazy val `opaque-type-aliases` = project.in(file("opaque-type-aliases"))

code-snippets/new-control-structure-syntax/src/main/scala/org/lunatech/dotty/NewControlStructures.scala

@@ -6,8 +6,6 @@ object NewControlStructures {
   val xs = Seq(1, 2, 3)
   val ys = Seq(3, 4, 5)
 
-  def body: Int = 6
-
   if x < 0 then "negative"
   else if x == 0 then "zero"
   else "positive"
@@ -26,6 +24,12 @@ object NewControlStructures {
     y <- ys
   do println(x + y)
 
-  // try body
-  // catch case ex: IOException => handle
+  def body: Int =
+    throw new IllegalArgumentException("Bad argument")
+    5
+
+  def handle = ???
+  val result =
+    try body
+    catch case ex: IllegalArgumentException => handle
 }

code-snippets/opaque-type-aliases/src/main/scala/opaquetypealiases/caseclasses/CaseClasses.scala

@@ -0,0 +1,11 @@
+package opaquetypelaliases.caseclasses
+
+case class Kilometres(value: Double)
+
+class Rocket(distanceTravelled: Kilometres):
+  def advance(distanceToAdvance: Kilometres): Rocket = new Rocket(
+    Kilometres(distanceTravelled.value + distanceToAdvance.value))
+
+val rocket = Rocket(Kilometres(1000))
+
+val r1 = rocket.advance(Kilometres(5000))

code-snippets/opaque-type-aliases/src/main/scala/opaquetypealiases/opaquetypealias/OpaqueTypeAliases.scala

@@ -0,0 +1,21 @@
+package opaquetypelaliases.opaquetypealias
+
+object OpaqueTypeAliasesDefinitions:
+
+  opaque type Kilometres = Double
+  object Kilometres:
+    def apply(d: Double): Kilometres = d
+
+  opaque type Miles = Double
+  object Miles:
+    def apply(d: Double): Miles = d
+
+  extension (a: Kilometres)
+    @scala.annotation.targetName("plusKm")
+    def +(b: Kilometres): Kilometres = a + b
+    def toMiles: Miles = a / 1.6
+
+  extension (a: Miles)
+    @scala.annotation.targetName("plusMiles")
+    def +(b: Miles): Miles = a + b
+    def toKm: Kilometres = a * 1.6

code-snippets/opaque-type-aliases/src/main/scala/opaquetypealiases/opaquetypealias/UsingTheAliases.scala

@@ -0,0 +1,26 @@
+package opaquetypelaliases.opaquetypealias
+
+object UsingTheAliases {
+  import OpaqueTypeAliasesDefinitions.*
+
+  class Rocket(distanceTravelled: Kilometres):
+    def advance(distanceToAdvance: Kilometres): Rocket = new Rocket(distanceTravelled + distanceToAdvance)
+
+  type Conversion[A] = A => Kilometres
+  class Booster():
+    def advanceRocket[A: Conversion](rocket: Rocket, distanceToAdvance: A): Rocket = {
+      val distanceInKm = summon[Conversion[A]](distanceToAdvance)
+      rocket.advance(distanceInKm)
+    }
+
+  val rocket1 = new Rocket(Kilometres(0))
+  val rocket2 = new Rocket(Kilometres(0))
+  val booster = new Booster()
+
+  given Conversion[Kilometres] = identity
+  given Conversion[Miles] = _.toKm
+
+  val r1 = booster.advanceRocket(rocket1, Kilometres(100)) // No allocation of Kilometres object
+  val r2 = booster.advanceRocket(rocket2, Miles(200)) // No allocation of Miles object
+
+}

code-snippets/opaque-type-aliases/src/main/scala/opaquetypealiases/parametricpolymorphism/ParametricPolymorphism.scala

@@ -0,0 +1,25 @@
+package opaquetypelaliases.parametricpolymorphism
+
+case class Kilometres(value: Double) extends AnyVal
+case class Miles(value: Double) extends AnyVal
+
+class Rocket(distanceTravelled: Kilometres):
+  def advance(distanceToAdvance: Kilometres): Rocket = new Rocket(
+    Kilometres(distanceTravelled.value + distanceToAdvance.value))
+
+type Conversion[A] = A => Kilometres
+class Booster():
+  def advanceRocket[A: Conversion](rocket: Rocket, distanceToAdvance: A): Rocket = {
+    val distanceInKm = summon[Conversion[A]](distanceToAdvance)
+    rocket.advance(distanceInKm)
+  }
+
+val rocket1 = new Rocket(Kilometres(0))
+val rocket2 = new Rocket(Kilometres(0))
+val booster = new Booster()
+
+given Conversion[Kilometres] = identity
+given Conversion[Miles] = miles => Kilometres(miles.value * 1.6)
+
+val r1 = booster.advanceRocket(rocket1, Kilometres(100)) // Allocation of Kilometres object
+val r2 = booster.advanceRocket(rocket2, Miles(200))

code-snippets/opaque-type-aliases/src/main/scala/opaquetypealiases/subtyping/Subtyping.scala

@@ -0,0 +1,25 @@
+package opaquetypelaliases.subtyping
+
+sealed trait Distance extends Any
+case class Kilometres(value: Double) extends AnyVal with Distance
+case class Miles(value: Double) extends AnyVal with Distance
+
+class Rocket(distanceTravelled: Kilometres):
+  def advance(distanceToAdvance: Kilometres): Rocket = new Rocket(
+    Kilometres(distanceTravelled.value + distanceToAdvance.value))
+
+class Booster():
+  def advanceRocket(rocket: Rocket, distanceToAdvance: Distance): Rocket = {
+    val distanceInKm = distanceToAdvance match {
+      case miles: Miles   => Kilometres(miles.value * 1.6)
+      case km: Kilometres => km
+    }
+    rocket.advance(distanceInKm)
+  }
+
+val rocket1 = new Rocket(Kilometres(0))
+val rocket2 = new Rocket(Kilometres(0))
+val booster = new Booster()
+
+val r1 = booster.advanceRocket(rocket1, Kilometres(100)) // Allocation of Kilometres object
+val r2 = booster.advanceRocket(rocket2, Miles(200)) // Allocation of Miles object

code-snippets/opaque-type-aliases/src/main/scala/opaquetypealiases/valueclasses/ValueClasses.scala

@@ -0,0 +1,11 @@
+package opaquetypelaliases.valueclasses
+
+case class Kilometres(value: Double) extends AnyVal
+
+class Rocket(distanceTravelled: Kilometres):
+  def advance(distanceToAdvance: Kilometres): Rocket = new Rocket(
+    Kilometres(distanceTravelled.value + distanceToAdvance.value))
+
+val rocket1 = new Rocket(Kilometres(0))
+
+val rocket2 = rocket1.advance(Kilometres(12000))