Combine return and switch in C#

Question

How can I combine return and switch case statements in C#?

I want something like

return switch (a)
{
    case 1: "lalala"
    case 2: "blalbla"
    case 3: "lolollo"
    default: "default" 
};

I know about this solution

switch (a)
{
    case 1: return "lalala";
    case 2: return "blalbla";
    case 3: return "lolollo";
    default: return "default";
}

But I want to only use the return operator.

Answer 1

Note: As of C#8 (ten years later!) this is now possible, please see the answer below.

---

switch and return can't combine that way, because switch is a statement, not an expression (i.e., it doesn't return a value).
If you really want to use just a single return, you could make a Dictionary to map the switch variable to return values:

var map = new Dictionary<int, string>() 
{
    {1, "lala"}, 
    {2, "lolo"}, 
    {3, "haha"}, 
};
string output;
return map.TryGetValue(a, out output) ? output : "default";