Read-only lists, NBT arrays, and ranges

Read a list through a read-only view

ImmutableList<T> provides reading, searching, and iteration. Use it for function parameters that only need to read a list.

func first(values: ImmutableList<int>): int {
    return values[0]
}

func main() {
    var source = [2, 4, 6]
    var view = source as ImmutableList<int>
    print(first(view))
    print(view.contains(4))
}

as creates a read-only view of shared storage. source can still change the list. view sees those changes. The read-only rule applies to the list itself. Mutable elements retain their own modification rules.

Use Minecraft NBT arrays

NBT arrays contain a specific integer kind. Use the B, I, or L marker.

func main() {
    var bytes = [B; 1b, 2b, 3b]
    var numbers = [I; 10, 20, 30]
    var longs = [L; 1L, 2L, 3L]
    print(bytes)
    print(numbers)
    print(longs)
}

The corresponding types are ByteArray, IntArray, and LongArray. Use these literals when game data requires the corresponding NBT types. Use list<T> for a general mutable sequence.

Iterate over an integer range

func main() {
    for (index: 1..3) {
        print(index)
    }
}

The range includes both endpoints. This loop prints 1, 2, and 3. Integer variables can also supply the bounds. The loop captures its bounds before iteration. index contains the current iteration value.