fix: feedback ex2

src/main/scala/TopSongs/TopSongs.scala

@@ -1,10 +1,10 @@
 package TopSongs
-import scala.io.Source
 import java.io.File
 import com.github.tototoshi.csv._
 
-trait Person:
+trait Person {
   val name: String
+}
 
 case class Artist(name: String) extends Person
 case class Writer(name: String) extends Person
@@ -45,10 +45,9 @@ class Song(
 )
 
 
-object TopSongs {
-  var songs: List[Song] = List()
-  def addSong(song: Song): Unit = {
-    songs = song :: songs
+case class TopSongs(songs: List[Song] = List()) {
+  def addSong(song: Song): TopSongs = {
+    TopSongs(song :: songs)
   }
   def printSongs(): Unit = {
     songs.foreach(song => println(
@@ -62,7 +61,7 @@ object TopSongs {
 
 @main def main(): Unit =
   // create a new TopSongs object
-  val topSongs = TopSongs
+  var topSongs = TopSongs()
 
   val reader = CSVReader.open(new File("src/main/resources/songs.csv"))
   val allRows = reader.allWithHeaders()
@@ -79,7 +78,7 @@ object TopSongs {
     )
 
     // add the song to the TopSongs object
-    topSongs.addSong(s)
+    topSongs = topSongs.addSong(s)
   }
   reader.close()