type-diagnostics.scala:4: error: type mismatch;
 found   : scala.collection.Set[String]
 required: scala.collection.immutable.Set[String]
  def f = Calculator("Hello",binding.keySet)
                                     ^
type-diagnostics.scala:13: error: type mismatch;
 found   : List[a(in method f2)]
 required: List[a(in method f1)]
      y match { case y1: List[a] => f3(x, y1) }
                                          ^
type-diagnostics.scala:17: error: type mismatch;
 found   : String(in method f2)
 required: java.lang.String
  def f2[String](s: String) = strings(List(s))
                                           ^
three errors found