Different output of matching on sequence in Scala 2.8

I'm a newbie to scala. I'm trying an example from the book "Programming Scala". The example can be get from here

The output under Scala 2.8 RC6: List: List: List:

I got the expected result under Scala 2.7.7: List: 1 3 23 90 List: 4 18 52 List:

I don't know why i开发者_Go百科t doesn't work on Scala 2.8. Please help me to figure it out.

The code works fine in Scala 2.8 RC6. Try to re-install it.