Given a set represented as a String, we can compute its powerset using foldLeft, as shown below.
| def powerset(s: String) = | |
| s.foldLeft(Set("")) { | |
| case (acc, x) => acc ++ acc.map(_ + x) | |
| } |
Isn’t this approach quite concise and elegant? Following snippet shows a pretty-printed output from powerset for a set: "abc".
scala> powerset("abc").toList sortWith ( _ < _) mkString "\n"
res3: String = "
| a
| ab
| abc
| ac
| b
| bc
| c"
Following is a F# implementation of this same function.
| let powerset (s:string): Set<string> = | |
| s.ToCharArray() | |
| |> Array.fold( | |
| fun (acc: Set<string>) x -> acc + (Set.map(fun y -> x.ToString()+y) acc) | |
| ) (Set.empty.Add("")) |
