# DataFusion Nested Type Function Library
[DataFusion][df] is an extensible query execution framework, written in Rust, that uses Apache Arrow as its in-memory format.
This crate contains functions for working with arrays, maps and structs, such as `array_append` that work with
`ListArray`, `LargeListArray` and `FixedListArray` types from the `arrow` crate.
Most projects should use the [`datafusion`] crate directly, which re-exports
this module. If you are already using the [`datafusion`] crate, there is no
reason to use this crate directly in your project as well.
[df]: https://crates.io/crates/datafusion
[`datafusion`]: https://crates.io/crates/datafusion