Array

Array<Type, N> is an stack-allocated vector of maximum capacity N, but not restricted to having an exact amount of elements as [Type; N].

Usage

use stack_array::Array;

let mut array = Array::<u8, 5>::new();

array.push(0);
array.push(3);

array.extend([1, 2]);

The Array type exposes an API similar to that of Vec with common functions:

• .push(Type) -> (),
• .pop() -> Option<Type>,
• .extend(IntoIterator<Item = Type>) -> (),
• .clear() -> (),
• .insert(usize, Type) -> (),
• .remove(usize) -> Type,
• .swap_remove(usize) -> Type,
• .retain(impl FnMut(&mut Type) -> bool) -> (),
• .dedup() -> (),
• .dedup_with(impl FnMut(&mut Type, &mut Type) -> bool) -> (),
• .dedup_by_key<K: PartialEq>(impl FnMut(&mut Type) -> K) -> (),
• .drain(impl RangeBounds<usize>) -> Self

The type implements Deref<Target = [Type]> along with DerefMut to access the methods of the slice type. There are also specialized functions for resizing the array.

Furthermore, most of its methods and implementations use cutting-edge nightly const-features, which allows for complex compile-time constants:

#![allow(incomplete_features)]

#![feature(generic_const_exprs)]
#![feature(const_convert)]
#![feature(const_trait_impl)]

use stack_array::Array;

static ARRAY: Array<u8, 6> = const {
    let mut instance = Array::<u8, 6>::from([1, 2, 3]);
    instance.push(4);
    instance.insert(0, 0);
    instance.pop().unwrap();
    instance
};

Performance

Array is stack-allocated, which means it does not make use of any allocator and maintains items inlined on the runtime stack or in the program memory.

	Array	Vec	ArrayVec	SmallVec
pushpop	845M/s	818M/s	826M/s	244M/s

Iterations per second, measured with rustc 1.100.0-nightly (e71c0f1e3 2026-08-18) on a MacBook M4.

When to use this type

This type should be used when you need to store a finite and reasonable number of elements in a list, and you care about performance.