feat: change Slot trait to enum

Author: PaoloPenazzi

src/main/scala/Slot.scala

@@ -1,20 +1,29 @@
-trait Slot:
-  /**
-   * This method is used to associate a value to a path.
-   * @param value the value to be associated with the path
-   * @return a tuple containing a path and the corresponding value
-   */
-  def -> (value: Any): (Path, Any) = (Path(this), value)
-
-  /**
-   * Creates a path by concatenating this slot with the given slot.
-   * @param slot the slot to be concatenated
-   * @return a path
-   */
-  def /(slot: Slot): Path = Path(this, slot)
+/**
+ * This enum defines the different slots that can be used.
+ */
+enum Slot:
+  case Nbr(index: Int)
+  case Rep(index: Int)
+  case FoldHood(index: Int)
+  case Branch(index: Int, tag: Boolean)
 
 object Slot:
-  final case class Nbr(index: Int) extends Slot
-  final case class Rep(index: Int) extends Slot
-  final case class FoldHood(index: Int) extends Slot
-  final case class Branch(index: Int, tag: Boolean) extends Slot
+  extension (slot: Slot)
+    /**
+     * This method is used to associate a value to a path.
+     *
+     * @param value the value to be associated with the path
+     * @return a tuple containing a path and the corresponding value
+     */
+    def ->(value: Any): (Path, Any) = (Path(slot), value)
+    /**
+     * Creates a path by concatenating this slot with the given slot.
+     *
+     * @param slot the slot to be concatenated
+     * @return a path
+     */
+    def /(other: Slot): Path = Path(slot, other)
+
+
+
+