Const Generics: How We Cut 85% of Our Code and Got Faster

Const generics, introduced in Rust with the unstable const_generics feature (now stabilized in Rust 1.51 and later), allow for compile-time parameters that can be used to specify sizes of arrays or other fixed-size types. This enables a variety of performance optimizations by eliminating dynamic allocations and enabling more aggressive compiler optimizations.

Here are some key patterns where const generics can significantly improve performance, safety, and code quality:

Pattern 1: Fixed-Size Arrays

Using const generics for fixed-size arrays allows you to create stack-allocated buffers that do not require heap allocation. This is particularly useful in scenarios where the size of data structures is known at compile time.

rust
 
1struct Packet<const HEADER_SIZE: usize, const PAYLOAD_SIZE: usize> {
2    header: [u8; HEADER_SIZE],
3    payload: [u8; PAYLOAD_SIZE],
4}
5
6impl<const H: usize, const P: usize> Packet<H, P> {
7    fn from_bytes(data: &[u8; H + P]) -> Self {
8        let mut header = [0u8; H];
9        let mut payload = [0u8; P];
10
11        header.copy_from_slice(&data[..H]);
12        payload.copy_from_slice(&
13
14[Read the full article at DEV Community](https://dev.to/speed_engineer/const-generics-how-we-cut-85-of-our-code-and-got-faster-1oam)
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