TypesExercises solutions

src/main/scala/introcourse/level02/TypesExercises.scala

@@ -49,7 +49,7 @@ object TypesExercises {
     **/
   def showPerson1(person: Person): String =
     person match {
-      case Person(name, age) => s"${???} is ${???} years old"
+      case Person(name, age) => s"$name is ${age} years old"
     }
 
   /**
@@ -58,7 +58,7 @@ object TypesExercises {
     * Hint: Navigate the Person class' fields using the "." operator
     */
   def showPerson2(person: Person): String =
-    s"${???} is ${???} years old"
+    s"${person.name} is ${person.age} years old"
 
   /**
     * Write a function that changes the age of a person.
@@ -72,7 +72,7 @@ object TypesExercises {
     *
     * Hint: Use the .copy method
     */
-  def changeAge(newAge: Int, person: Person): Person = ???
+  def changeAge(newAge: Int, person: Person): Person = person.copy(age = newAge)
 
   /**
     * Let's look at another data type.
@@ -95,7 +95,7 @@ object TypesExercises {
     *
     * You can solve this like how you solved `showPerson1` or `showPerson2`.
     */
-  def showWallet(wallet: Wallet): String = ???
+  def showWallet(wallet: Wallet): String = s"The wallet amount is ${wallet.amount}"
 
   /**
     * Here is another example of working with immutable values.
@@ -106,7 +106,10 @@ object TypesExercises {
     *
     * Hint: You need to calculate the new amount first.
     **/
-  def purchase(cost: Double, wallet: Wallet): Wallet = ???
+  def purchase(cost: Double, wallet: Wallet): Wallet = {
+    val newBalance = wallet.amount - cost
+    wallet.copy(amount = newBalance)
+  }
 
   /**
     * *********************************************
@@ -140,7 +143,15 @@ object TypesExercises {
   /**
     * Implement the following showTrafficLightStr function to pass all your tests!
     */
-  def showTrafficLightStr(trafficLight: String): String = ???
+  def showTrafficLightStr(trafficLight: String): String = {
+    trafficLight match {
+      case "red" => "The traffic light is red"
+      case "yellow" => "The traffic light is yellow"
+      case "green" => "The traffic light is green"
+      case "flashing" => "The traffic light is flashing"
+      case _ => "The traffic light is invalid"
+    }
+  }
 
 
   /**
@@ -180,7 +191,7 @@ object TypesExercises {
     * This technique helps you make invalid states/values irrepresentable in your programs
     */
   enum TrafficLight {
-    case Red, Yellow, Green
+    case Red, Yellow, Green, Flashing
   }
 
   // Scala 2.12 equivalent syntax
@@ -209,7 +220,15 @@ object TypesExercises {
     * Hint: Use pattern matching
     **/
 
-  def showTrafficLight(trafficLight: TrafficLight): String = ???
+  def showTrafficLight(trafficLight: TrafficLight): String = {
+    val colour = trafficLight match
+      case TrafficLight.Red => "red"
+      case TrafficLight.Yellow => "yellow"
+      case TrafficLight.Green => "green"
+      case TrafficLight.Flashing => "flashing"
+
+    s"The traffic light is $colour"
+  }
 
   /**
     * *********************************************************

src/test/scala/introcourse/level02/TypesExercisesTest.scala

@@ -90,11 +90,15 @@ class TypesExercisesTest extends AnyFunSpec with TypeCheckedTripleEquals {
     }
 
     it("should return a default on other inputs") {
-      ???
+      val str = showTrafficLightStr("foo")
+
+      assert(str === "The traffic light is invalid")
     }
 
     it("should show flashing") {
-      ???
+      val str = showTrafficLightStr("flashing")
+
+      assert(str === "The traffic light is flashing")
     }
 
   }
@@ -120,7 +124,9 @@ class TypesExercisesTest extends AnyFunSpec with TypeCheckedTripleEquals {
     }
 
     it("should show Flashing") {
-      ???
+      val str = showTrafficLight(Flashing)
+
+      assert(str === "The traffic light is flashing")
     }
 
   }