#arithmetic-operations #arithmetic #operations #ord #cmp #options

no-std option-operations

Traits and auto-implementations to improve arithmetic operations usability when dealing with Options

6 releases (breaking)

0.5.0 Aug 15, 2022
0.4.1 Jun 29, 2022
0.4.0 Oct 24, 2021
0.3.0 Oct 18, 2021
0.1.0 Oct 7, 2021

#326 in Math

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option-operations

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option-operations provides traits and auto-implementations to improve arithmetic operations usability when dealing with Options.

Example

Dealing with two Options, can lead to verbose expressions:

let lhs = Some(1u64);
let rhs = Some(u64::MAX);

assert_eq!(
    lhs.zip(rhs).map(|(lhs, rhs)| lhs.saturating_add(rhs)),
    Some(u64::MAX),
);

Thanks to the trait OptionSaturatingAdd we can write:

assert_eq!(
    lhs.opt_saturating_add(rhs),
    Some(u64::MAX),
);

The trait can also be used with the inner type:

assert_eq!(
    lhs.opt_saturating_add(u64::MAX),
    Some(u64::MAX),
);

assert_eq!(
    1.opt_saturating_add(rhs),
    Some(u64::MAX),
);

Alternative to PartialOrd for Option<T>

Another purpose is to workaround the PartiaOrd implementation for Option<T>, which uses the declaration order of the variants for Option. None appearing before Some(_), it results in the following behavior:

let some_0 = Some(0);
let none: Option<u64> = None;

assert_eq!(none.partial_cmp(&some_0), Some(Ordering::Less));
assert_eq!(some_0.partial_cmp(&none), Some(Ordering::Greater));

In some cases, we might consider that None reflects a value which is not defined and thus can not be compared with Some(_).

assert_eq!(none.opt_cmp(&some_0), None);
assert_eq!(some_0.opt_cmp(&none), None);

Of course, this is consistent with other usual comparisons:

assert_eq!(none.opt_lt(&some_0), None);
assert_eq!(none.opt_min(&some_0), None);

LICENSE

This crate is licensed under either of

at your option.

Dependencies