alias U8Box = Box<u8>

type Box<T: Type> {
    value: T,
}

type Slot<T: Type> {
    item: T,
    seen: Bool = false,
}

type Pair<T: Type, U: Type> {
    left: T,
    right: U,
}

pub fn main(world: World) -> Void raises {
    let nested: Pair<Box<i32>, Slot<u8>> = Pair { left: Box { value: 42 }, right: Slot { item: 7_u8 } }
    let aliased: U8Box = Box { value: nested.right.item }
    if nested.left.value == 42 && !nested.right.seen && aliased.value == 7_u8 {
        check world.out.write("generic shape nested defaults alias ok\n")
    }
}