scala3-Matchable-inferred-supertype.scala

scala> val seq = Seq(1, 2, 3.14, 5.5F, "one", "four", true, (6, 7)) 
     |
val seq: Seq[Matchable] = List(1, 2, 3.14, 5.5, one, four, true, (6,7))

scala> val result = seq.map {
     |   case 1                   => "int 1"                           // <2>
     |   case i: Int              => s"other int: $i"
     |   case d: (Double | Float) => s"a double or float: $d"          // <3>
     |   case "one"               => "string one"                      // <4>
     |   case s: String           => s"other string: $s"
     |   case (x, y)              => s"tuple: ($x, $y)"                // <5>
     |   case unexpected          => s"unexpected value: $unexpected"  // <6>
     | }
     |
val result: Seq[String] = List(int 1, other int: 2, a double or float: 3.14, a double or float: 5.5, string one, other string: four, unexpected value: true, tuple: (6, 7))