# Equivalent
[](https://crates.io/crates/equivalent)
[](https://docs.rs/equivalent)
`Equivalent` and `Comparable` are Rust traits for key comparison in maps.
These may be used in the implementation of maps where the lookup type `Q`
may be different than the stored key type `K`.
* `Q: Equivalent<K>` checks for equality, similar to the `HashMap<K, V>`
constraint `K: Borrow<Q>, Q: Eq`.
* `Q: Comparable<K>` checks the ordering, similar to the `BTreeMap<K, V>`
constraint `K: Borrow<Q>, Q: Ord`.
These traits are not used by the maps in the standard library, but they may
add more flexibility in third-party map implementations, especially in
situations where a strict `K: Borrow<Q>` relationship is not available.
## License
Equivalent is distributed under the terms of both the MIT license and the
Apache License (Version 2.0). See [LICENSE-APACHE](LICENSE-APACHE) and
[LICENSE-MIT](LICENSE-MIT) for details. Opening a pull request is
assumed to signal agreement with these licensing terms.
