Connected to Huly®: V_0.6-22949

Interesting. Seems required unsafe you are mentioning "tries" to protect the mutable array reference and the extra parentheses are doing the same. But using the reference later is more interesting. The reference (does not need to be mutable) can be used as argument of a function where the value referenced can be modified with unsafe de-reference *.

But unsafe de-reference is more powerful than V mutability because the array does not need to be mutable, the reference does not need to be surrounded with unsafe and finally the inmutable array can be mutated.

In next example both arrays mutable a and immutable `b are modified:

fn set_1000(i &int) {
	old := *i
	unsafe{
		*i = 1000
	}
	println('old:${old} new:${*i}')
}

fn main() {
	mut a := [1, 2, 3]
	ref := &(a[1]) // or ref := unsafe{ &a[1] }
	set_1000(ref)
	assert a == [1, 1000, 3]
	
	b := [4, 5, 6] // immutable
	set_1000(&b[1])
	assert b == [4, 1000, 6] // changed though b is immutable
}

An array actually is a reference when passed by, so we can pass mutable arrays for modification or non mutable for only reading.