README.md
1[](https://crates.io/crates/generic-array)
2[](https://travis-ci.org/fizyk20/generic-array)
3# generic-array
4
5This crate implements generic array types for Rust.
6
7**Requires minumum Rust version of 1.36.0, or 1.41.0 for `From<[T; N]>` implementations**
8
9[Documentation](http://fizyk20.github.io/generic-array/generic_array/)
10
11## Usage
12
13The Rust arrays `[T; N]` are problematic in that they can't be used generically with respect to `N`, so for example this won't work:
14
15```rust
16struct Foo<N> {
17 data: [i32; N]
18}
19```
20
21**generic-array** defines a new trait `ArrayLength<T>` and a struct `GenericArray<T, N: ArrayLength<T>>`, which let the above be implemented as:
22
23```rust
24struct Foo<N: ArrayLength<i32>> {
25 data: GenericArray<i32, N>
26}
27```
28
29The `ArrayLength<T>` trait is implemented by default for [unsigned integer types](http://fizyk20.github.io/generic-array/typenum/uint/index.html) from [typenum](http://fizyk20.github.io/generic-array/typenum/index.html) crate:
30
31```rust
32use generic_array::typenum::U5;
33
34struct Foo<N: ArrayLength<i32>> {
35 data: GenericArray<i32, N>
36}
37
38fn main() {
39 let foo = Foo::<U5>{data: GenericArray::default()};
40}
41```
42
43For example, `GenericArray<T, U5>` would work almost like `[T; 5]`:
44
45```rust
46use generic_array::typenum::U5;
47
48struct Foo<T, N: ArrayLength<T>> {
49 data: GenericArray<T, N>
50}
51
52fn main() {
53 let foo = Foo::<i32, U5>{data: GenericArray::default()};
54}
55```
56
57In version 0.1.1 an `arr!` macro was introduced, allowing for creation of arrays as shown below:
58
59```rust
60let array = arr![u32; 1, 2, 3];
61assert_eq!(array[2], 3);
62```
63
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