extern crate typed_arena;
use typed_arena::Arena;

#[derive(Debug, Clone)]
struct Node {
  v: i64,
  l: Option<&Node>,
  r: Option<&Node>,
}

fn ins(arena: &Arena<Node>, t: Option<&Node>, v: i64) -> Option<&Node> {
  match t {
    None =>
      Some(arena.alloc(&Node{v: v, l: None, r: None})),
    Some(n) =>
      if v < n.v {
        Some(arena.alloc(&Node{v: n.v, l: ins(n.l, v), r: n.r}))
      } else {
        Some(arena.alloc(&Node{v: n.v, l: n.l, r: ins(n.r, v)}))
      }
  }
}

fn main() {
  let mut arena = Arena::new();
  let t = arena.alloc(Node{v: 5, l: None, r: None});
  let t2 = ins(arena, Some(&t), 3);
  println!("Hello World! {:?}", t2);
}