How to get a scala Map value, when the key is a tuple in which only the first element is known?

Question

Suppose I have a scala immutable Map[(String, Boolean), Set[String]], e.g.:

val myMap = Map(("a",true) -> Set("b","c"))

Now suppose I only know the first element of the key tuple, "a". Can (and how if yes) I get the map's value for this key if:

1) I know that the key could either be ("a", true) or ("a", false) (there cannot be two keys with the same String as the first element)

2) I don't know that, in which case I wish to get some kind of concatenation on the possible two values, such as v1.union(v2) or v1 ++ v2, etc.

Is there any scala "magic" I could use, like myMap.get(("a", Any))?

Answer 1

In general, hash maps does not work like that, at least efficiently -- you still can scan map linearly and pick first key that matches criteria. In your particular case you can simply try to lookup record twice -- first with (key, true), then if nothing is found (key, false)