#collection #non-empty #vector #one-or-more

no-std mitsein

Strongly typed APIs for non-empty collections and views

3 unstable releases

0.1.1 Jun 20, 2024
0.1.0 Jun 20, 2024
0.0.0 Jun 13, 2024

#400 in Data structures

Download history 55/week @ 2024-06-07 258/week @ 2024-06-14 84/week @ 2024-06-21

397 downloads per month

MIT license

1.5K SLoC

Mitsein is a Rust library that provides strongly typed APIs for non-empty collections and views, including (but not limited to) iterators, slices, and vectors.

GitHub docs.rs crates.io

Basic Usage

Allocating a Vec1 from one or more items (infallibly):

use mitsein::vec1::{vec1, Vec1};

let xs = Vec1::from_item(0i32);
let xs = Vec1::from([0i32, 1, 2]);
let xs = Vec1::from_head_and_tail(0i32, [1, 2]);

let xs = vec1![0i32, 1, 2];

Allocating a Vec1 from zero or more items (fallibly):

use mitsein::vec1::Vec1;

let ys = vec![0i32, 1, 2];

let xs = Vec1::try_from(ys)?;
let xs = Vec1::try_from(&[0i32, 1, 2])?;
let xs = Vec1::try_from_iter([0i32, 1, 2])?;

Mapping over items in Vec1s:

use mitsein::prelude::*;
use mitsein::vec1::Vec1;

let xs = Vec1::from([0i32, 1, 2]);
let ys: Vec1<_> = xs.into_iter1().map(|x| x + 1).collect();

Bridging between Iterator and Iterator1:

use mitsein::iter1;
use mitsein::prelude::*;
use mitsein::vec1::Vec1;

let xs = iter1::from_head_and_tail(0i32, [1, 2]);
let xs: Vec1<_> = xs.into_iter().skip(3).or1([3]).collect();
assert_eq!(xs.as_slice(), &[3]);

let xs = Vec1::from([0i32, 1, 2]);
let (has_zero, remainder) = xs.iter1().any(|x| *x == 0);
if has_zero {
    let xs: Vec1<_> = remainder.or_else1(|| iter1::from_item(&0i32)).collect();
    assert_eq!(xs.as_slice(), &[&1, &2]);

Features and Comparisons

By providing non-empty APIs over both collections and views (i.e., slices and iterators), Mitsein separates concerns just like standard collection and iterator APIs. Unlike many other non-empty collection implementations, Mitsein need not expose combinatorial sets of inherent iterator-like functions in collections for each pair of receiver and operation. For example, the vec1 crate supports map operations over its Vec1 type via the Vec1::mapped, Vec1::mapped_ref, and Vec1::mapped_mut functions. Mitsein instead exposes map operations via Iterator1, which can support any non-empty view or collection with a more typical API.

Non-empty view APIs also enable borrowing, so Mitsein collection types support copy-on-write via the standard Cow type, unlike many other non-empty collection implementations.

Non-empty iterator APIs are largely compatible with standard iterators, allowing non-empty collections to interact ergonomically with collection of zero or more items. Mitsein views and collections use more familiar syntax for mapping, taking, chaining, etc.

Items are stored contiguously or otherwise in a homogeneous manner in Mitsein. This means that no head item is allocated diffently. For example, the nonempty crate directly exposes a head item that is, unlike tail items, not allocated on the heap. This can potentially cause surprising or poor performance when the item type is large, as the head item is stack allocated.

Cargo Features

Mitsein provides some optional features and integrations via the following Cargo features.

Feature Default Dependencies Description
alloc Yes alloc Non-empty collections that allocate, like Vec1.
itertools No itertools Combinators from itertools for Iterator1.
serde No serde, serde_derive De/serialization of non-empty collections with serde.