Function i8_array 

pub fn i8_array<T, S>(array: T, serializer: S) -> Result<S::Ok, S::Error>
where
    T: IntoIterator,
    <T as IntoIterator>::Item: Borrow<i8>,
    S: Serializer,

This function provides serde serialization support for NBT type ByteArray.

It should be used in conjunction with serde’s field annotation serialize_with. In the following example byte_data will be serialized as a ByteArray instead of a List of Bytes:

extern crate serde;
use nbt::to_writer;
use serde::Serialize;

let mut serialized = Vec::new();

// Declare your struct
#[derive(Serialize)]
struct Sheep {
    #[serde(serialize_with="nbt::i8_array")]
    byte_data: Vec<i8>,
}

// Serialize to NBT!
to_writer(
    &mut serialized,
    &Sheep {
        byte_data: vec![0x62, 0x69, 0x6E, 0x61, 0x72, 0x79, 0x20, 0x73, 0x68, 0x65, 0x65, 0x70],
    },
    None
).unwrap();

print!("Serialized: {:?}", serialized);