Using Scala's worksheet, clarification needed [closed]

Question

The following snippet compiles and runs fine

When using as part of worksheet, i see error

Why is this please?

Answer 1

It's probably just a bug/missing feature.

By the way, you could write joiner like the following code to get the same behaviour, and it also will avoid the worksheet problem.

def joiner(strings: List[String], separator: String = " ") = 
  strings.mkString(separator)