How to create all possible combinations from the elements of a list?

Question

I have the following list:

List(a, b, c, d, e)

How to create all possible combinations from the above list?

I expect something like:

Answer 1

def combine(in: List[Char]): Seq[String] = 
    for {
        len <- 1 to in.length
        combinations <- in combinations len
    } yield combinations.mkString