What's the meaning of #:: in Scala?

Question

What is the meaning of x#::xs in Scala?

for example

 case x #:: xs => {

In this case x was a Stream but I suppose that the same syntax is valid also for list ecc...

Answer 1

It's an extractor for pattern matching streams . This is not valid for Lists. The lists have :: (note there is no # in the list).

The meaning of the case x #:: xs => is that when the pattern is matched, the x will contain the head of the stream, and the xs will contain the rest of the stream (tail).

Check the stream documentation for examples on how to define streams.