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:

a ab abc  

Answer 1

Or you could use the subsets method. You'll have to convert your list to a set first though.

scala> List(1,2,3).toSet[Int].subsets.map(_.toList).toList res9: List[List[Int]] = List(List(), List(1), List(2), List(3), List(1, 2), List(1, 3), List(2, 3), List(1, 2, 3)) 

Answer 2

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