I was wondering how to serialize and deserialize a binary tree efficiently. This is what I currently have

```
type binary_tree('a) =
| Leaf
| Node('a, binary_tree('a), binary_tree('a));
type str_binary_tree = binary_tree(string);
let node: str_binary_tree =
Node("12", Node("11", Leaf, Leaf), Node("14", Leaf, Leaf));
let serialize = (node: str_binary_tree): string => {
let rec aux = (n, acc) =>
switch (n) {
| Leaf => acc ++ "-1"
| Node(x, l, Leaf) => aux(l, acc ++ " " ++ x ++ " " ++ "-1 ")
| Node(x, Leaf, r) => aux(r, acc ++ " " ++ "-1" ++ " " ++ x)
| Node(x, l, r) => aux(l, acc ++ x) ++ aux(r, acc)
};
aux(node, "");
};
let splitString = str => Js.String.split(" ", str);
Js.log(splitString(serialize(node)));
let rec deserialize = lst => {
switch (lst) {
| [] => Leaf
| [x, ...xs] =>
x === "-1" ? deserialize(xs) : Node(x, deserialize(xs), deserialize(xs))
};
};
Js.log(splitString(serialize(node)) |> Array.to_list |> deserialize);
```

The serialization seems to work, but the deserialization isn’t working as I expect, what changes do I need to make for this to work ?

Thanks