A generic implementation of a sum type (or discriminated union). It provides enum Or<T1, T2, ..., N> types as a counterpart to tuples.

Features

• has #![no_std] and #![forbid(unsafe_code)]
• supports the applicable core traits
• features = ["iter"] (default): supports the Into/Iterator traits
• features = ["future"] (default): supports the Into/Future traits
• features = ["serde"]: supports the Serialize and Deserialize traits
• features = ["rayon"]: supports the ParallelIterator family of traits
• features = ["or16"]: for up to Or16
• features = ["or32"]: for up to Or32

Cheat Sheet

use orn::*;

/// Using the `tn` methods, items of an `Or` value can be retrieved.
pub fn retrieve_dynamically(input: Or3<u8, usize, [char; 1]>) {
    let _a: Option<u8> = input.t0();
    let _b: Option<usize> = input.t1();
    let _c: Option<[char; 1]> = input.t2();
}

/// Using the `At<I>` trait, items of an `Or` value can be retrieved
/// generically.
pub fn retrieve_statically(input: Or4<char, bool, isize, u32>) {
    let _a: Option<char> = At::<0>::at(input);
    let _b: Option<bool> = At::<1>::at(input);
    let _c: Option<isize> = At::<2>::at(input);
    let _d: Option<u32> = At::<3>::at(input);
}

/// Often, the type of iterator is conditional to some input value. Typically,
/// to unify the return type, one would need to implement a custom iterator, but
/// here `orn` types are used instead.
#[cfg(feature = "iter")]
pub fn unify_divergent_iterators(array_or_range: bool) -> impl Iterator<Item = u8> {
    if array_or_range {
        Or2::T0([1u8, 2u8])
    } else {
        Or2::T1(0u8..10u8)
    }
    .into_iter()
    // The item of the `Or` iterator is `Or<u8, u8>`. `Or::into` collapses an `Or` value into a
    // specified type.
    .map(Or2::into)
}

#[cfg(feature = "rayon")]
use rayon::prelude::*;
/// With `features = ["rayon"]`, `rayon`'s `ParallelIterator` family of traits
/// can be used similarly to the `Iterator` trait.
#[cfg(feature = "rayon")]
pub fn unify_divergent_parallel_iterators(
    array_or_range: bool,
) -> impl ParallelIterator<Item = u8> {
    if array_or_range {
        Or2::T0([1u8, 2u8])
    } else {
        Or2::T1(0u8..10u8)
    }
    .into_par_iter()
    // The item of the `Or` iterator is `Or<u8, u8>`. `Or::into` collapses an `Or` value into a
    // specified type.
    .map(Or2::into)
}

fn main() {}