Passing parameters to mutator functions in Scala

Question

I'm playing around in Scala to try and get the hang of it, so this code sample is simply academic.

I'm trying to pass a mutable List to a function, have that function perform work on it, and then after the function call I can use the updated list.

var data: List[Int] = List()

// Call to function to fill a list
data = initList(data)

// Output only 0-100
data.foreach( num => if (num < 100) { println(num) })

def initList(var data: List[Int]) : List[Int] = {

    for ( i <- 0 to 1000 )
    {
        data = i :: data
    }

    data = data.reverse
    data
}

The only code above that doesn't compile is the var in def initList(), and because data is then a val I cannot perform any mutations to it within the function.

Let me start by saying that I know in Scala, mutators are usually frowned upon, so I'm not only open to a direct answer to my question, but open to better ways to do it entirely. Occasionally in projects there is a piece of data that goes from place to place to be updated, but if you cannot pass data to a function to be changed then what is a good alternative?

I've read through tutorials and google'd for this, I'm assuming I can't find much about it because it's not usually done this way in Scala.