Moved underscore tutorial to Scala 2 module

Author: yadavan88

scala-2-modules/scala2-core/README.md

@@ -8,4 +8,5 @@
 - [Introduction to Macros in Scala 2](https://www.baeldung.com/scala/scala2-macros)
 - [Demystifying View and Context Bounds](https://www.baeldung.com/scala/view-context-bounds)
 - [Introduction to Scala](https://www.baeldung.com/scala/scala-intro)
-- [Exception Handling in Scala](https://www.baeldung.com/scala/exception-handling)
+- [Exception Handling in Scala](https://www.baeldung.com/scala/exception-handling)
+- [Usages of Underscore (_) in Scala](https://www.baeldung.com/scala/underscore)

scala-core-modules/scala-core-2/src/main/scala/com/baeldung/scala/underscore/UnderscoreUsages.scala renamed to scala-2-modules/scala2-core/src/main/scala-2/com/baeldung/scala/underscore/UnderscoreUsages.scala

@@ -2,7 +2,7 @@ package com.baeldung.scala.underscore
 
 object UnderscoreUsages {
 
-  def getLength(x: List[List[?]]): Int = x.length
+  def getLength(x: List[List[_]]): Int = x.length
 
   def itemTransaction(price: Double): String = {
     price match {
@@ -33,7 +33,7 @@ object UnderscoreUsages {
     }
   }
 
-  def list_++(list: List[?]): List[?] = List.concat(list, list)
+  def list_++(list: List[_]): List[_] = List.concat(list, list)
 
   trait ObjectContainer[T[_]] { // higher kinded type parameter
     def checkIfEmpty[A](collection: T[A]): Boolean

scala-core-modules/scala-core-2/src/test/scala/com/baeldung/scala/underscore/UnderscoreUsagesUnitTest.scala renamed to scala-2-modules/scala2-core/src/test/scala-2/com/baeldung/scala/underscore/UnderscoreUsagesUnitTest.scala

@@ -1,8 +1,9 @@
 package com.baeldung.scala.underscore
 
-import com.baeldung.scala.underscore.UnderscoreUsages._
 import org.scalatest.matchers.should.Matchers
 import org.scalatest.wordspec.AnyWordSpec
+import UnderscoreUsages._
+
 class UnderscoreUsagesUnitTest extends AnyWordSpec with Matchers {
 
   "The underscore" should {
@@ -58,20 +59,20 @@ class UnderscoreUsagesUnitTest extends AnyWordSpec with Matchers {
       e shouldBe "e"
     }
     "work in reassigning a a function to a value" in {
-      val times = multiplier
+      val times = multiplier _
       multiplier(8, 13) shouldBe times(8, 13)
     }
     "work in converting a sequence to variable arguments" in {
       val sumable = Seq(4, 5, 10, 3)
-      val sumOfSumable = sum(sumable*)
+      val sumOfSumable = sum(sumable: _*)
       sumOfSumable shouldBe 22
     }
     "generate a partially applied function" in {
       val sumToTen = sum(10, _: Int)
       val sumFiveAndTen = sumToTen(5)
       sumFiveAndTen shouldBe 15
 
-      val foo = bar(1, 2)
+      val foo = bar(1, 2) _
       foo("Some string", "Another string")(3 / 5, 6 / 5) shouldBe 1
     }
     "work in overriding a method's setter" in {

scala-core-modules/scala-core-2/README.md

@@ -9,7 +9,6 @@ This module contains articles about Scala's core features.
 - [Futures and Promises in Scala](https://www.baeldung.com/scala/futures-promises)
 - [Named and Default Arguments in Scala](https://www.baeldung.com/scala/named-default-arguments)
 - [Self-Type Annotation in Scala](https://www.baeldung.com/scala/self-type-annotation)
-- [Usages of Underscore (_) in Scala](https://www.baeldung.com/scala/underscore)
 - [A DSL for Writing “20 seconds” in Scala](https://www.baeldung.com/scala/dsl-writing-20-seconds)
 - [Error Handling in Scala](https://www.baeldung.com/scala/error-handling)
 - [Higher-Kinded Types](https://www.baeldung.com/scala/higher-kinded-types)