Start the interpreter and evaluate the following declaration
trait A { def f: Int = 0; }

the evaluate this declaration
class B extends A

The interpreter signals the following error:
<console>:1: class B needs to be abstract, since method f in trait A is not defined
class B extends A
      ^



Here is another example: start the interpreter, evalaute the expression List() and then evaluate\
 the following expression:
val x= <greetings>hello world</greetings>

This generates tens of error messages mainly about method that are not defined.