Initialize an empty tuple scala

Question

I want to create a mutable tuple in scala (String, Set[String]). And before I want to initialize it to an empty value first before adding to it

the set can not be initialized to empty set. The same for String. I'm getting an error saying class java.lang.String is not a value Is there a simple way to do that ? and What am I doing wrong

Answer 1

Empty Set can be defined like so

Set.empty[String]   // because assert(Set.empty[String].isEmpty)

Empty String can be defined like so

""                  // because assert("".isEmpty)

Empty tuple is not something Scala models as TupleN, I think. Instead it uses Unit type for it. Perhaps you are after something like so

val ta: (String, Set[String]) = ("", Set.empty)
val tb: (Option[String], Option[Set[String]]) = (None, None)
val tc: Option[(String, Set[String])] = None

The error message

class java.lang.String is not a value

means you are using a type where value is expected, for example, consider the difference between

Set[String]    // ok
Set(String)    // error