gistfile1.txt

tag treemap<@K, @V> {
    empty;
    node(K, V,
         {
             mutable left : @treemap<K,V>,
             mutable right : @treemap<K,V>
         });
}

fn insert<@K, @V>(m : &mutable treemap<K, V>, k : K, v : V) {
    alt m {
      empty. {
        m = node(k, v, {mutable left : @empty, mutable right : @empty});
      }
      node(kk, _, n) {
        if k < kk { insert(*n.left, k, v); }
        else { insert(*n.right, k, v); }
      }
    }
}