Multiple case receivers in Switch works in an non-obvious way

[emil14]

When using switch with multiple case receivers, it's important to understand that it works differently than in control flow languages. For example:

switch {
    ['Alice', 'Bob'] -> upper
    _ -> lower
}

Is not "if either Alice or Bob then do uppercase". It's a fan-in, which means Alice and Bob are concurrent to each other. Switch will select first value that will be sent as a case value, which is in this case random, because both values are message literals

[emil14]

Maybe it's possible to support this by having some special data-type that represents "one of"? Unions?