reliakit-collections

Bounded and reliability-oriented collection types for Rust.

reliakit-collections provides collection types with enforced size constraints. Bounds are expressed as const generic parameters and checked at construction time. Mutations that would violate the bounds return errors instead of panicking.

The crate has no dependencies and forbids unsafe code.

When To Use It

Use this crate when:

• a list must always have at least one element,
• a list must not exceed a known maximum size,
• you want mutation operations to be safe-by-default rather than checked at the call site,
• you are modeling domain concepts like a non-empty recipient list, a capped queue, or a fixed-size batch.

When Not To Use It

Do not use this crate as a replacement for:

• runtime-sized collections without known bounds — use std::collections directly,
• fixed-size stack-allocated arrays — use [T; N],
• NonEmptyVec<T> with no upper bound — that type is already in reliakit-primitives.

Installation

[dependencies]
reliakit-collections = "0.1"

For no_std environments:

[dependencies]
reliakit-collections = { version = "0.1", default-features = false, features = ["alloc"] }

Examples

Bounded recipient list

use reliakit_collections::BoundedVec;

type RecipientList = BoundedVec<String, 1, 10>;

let mut recipients = RecipientList::new(vec!["alice@example.com".into()]).unwrap();
recipients.push("bob@example.com".into()).unwrap();
assert_eq!(recipients.len(), 2);

Push and pop with bound enforcement

use reliakit_collections::BoundedVec;

let mut v = BoundedVec::<i32, 1, 3>::new(vec![1, 2, 3]).unwrap();

assert!(v.push(4).is_err()); // at capacity
assert_eq!(v.pop().unwrap(), 3);
assert!(v.pop().is_ok());    // len = 2, above minimum
assert!(v.pop().is_err());   // would go below minimum (1)

Exact-size collection

use reliakit_collections::BoundedVec;

// Must have exactly 3 elements
type Triple = BoundedVec<i32, 3, 3>;

assert!(Triple::new(vec![1, 2, 3]).is_ok());
assert!(Triple::new(vec![1, 2]).is_err());
assert!(Triple::new(vec![1, 2, 3, 4]).is_err());

Available Types

Feature Flags

no_std

The crate supports no_std environments when std is disabled and alloc is available.

Safety

This crate is #![forbid(unsafe_code)].

Minimum Supported Rust Version

Rust 1.85 stable. No nightly features are used.

Status

Active. Not yet published to crates.io.

Contributing

See CONTRIBUTING.md.

License

Licensed under the MIT License.