Make a variable single-assignment?

[Alex Rønne Petersen]

Hi,

Is there any way to make a variable single-assignment, regardless of its 
type? I.e.:

void foo()
{
     <some magical keyword?> int i = 0;
     i = 2; // Error: i cannot be reassigned
}

I realize const and immutable will do this, but they are transitive and 
infect the type, which I do *not* want. I simply want the variable to be 
single-assignment. Is it possible?

- Alex