How to return a function in scala

Question

How can I return a function side-effecting lexical closure¹ in Scala?

For instance, I was looking at this code sample in Go:

Answer 1

Slightly shorter, you don't need the return.

def fib() = {
    var a = 0
    var b = 1
    () => { 
        val t = a;
        a = b
        b = t + b
        b
    }
}