Variadic parameters

Place ... before the final parameter type:

fun sum(first: Int, rest: ...Int) Int {
    var total = first;
    var index: Int = 0;

    while index < rest.len {
        total = total + rest[index];
        index = index + 1;
    }
    return total;
}

Call the function with any number of trailing arguments:

var small = sum(1);
var larger = sum(1, 2, 3, 4);

Inside the function, the variadic parameter is available as a slice.

Forward variadic arguments

Prefix an existing slice, array, or variadic parameter with ...:

fun addTen(values: ...Int) Int {
    return sum(10, ...values);
}

You can include ordinary arguments before the forwarded sequence:

fun addPrefix(prefix: Int, values: ...Int) Int {
    return sum(prefix, 5, ...values);
}

Only the final parameter may be variadic.

External C variadic functions use a separate untyped declaration form, such as ext fun printf(format: String, ...) Int. See C interop.