uy

Compile-time unit safety for Rust. Catches unit errors at compile time with zero runtime cost.

See docs.rs/uy for the full API.

use uy::{Quantity, si};

let distance: Quantity<f32, si::m> = Quantity::new(100.0);
let time: Quantity<f32, si::s> = Quantity::new(9.58);
let speed: Quantity<f32, si::meter_per_second> = distance / time;

// This won't compile - can't add meters to seconds:
// let wrong = distance + time;

Installation

[dependencies]
uy = "0.3"

Usage

Basic quantities

use uy::{Quantity, si};

let mass: Quantity<f64, si::kg> = Quantity::new(75.0);
let force: Quantity<f64, si::N> = Quantity::new(100.0);

Unit algebra

Units combine through multiplication and division. All derived and compound units are just type aliases to combinations of Mul, Div, and base units:

use uy::{Quantity, Mul, Div, si};

// These are equivalent:
let v1: Quantity<f32, si::meter_per_second> = Quantity::new(10.0);
let v2: Quantity<f32, Div<si::m, si::s>> = Quantity::new(10.0);

// Unit algebra works automatically:
let length: Quantity<f32, si::m> = Quantity::new(5.0);
let width: Quantity<f32, si::m> = Quantity::new(3.0);
let area: Quantity<f32, si::square_meter> = length * width;  // m * m = m²

Prefix conversions

Scale is encoded in the type via TenTo<N>. Prefixes like milli and kilo are type aliases:

use uy::{Quantity, si};

// si::milli<U> is just Mul<U, TenTo<-3>>
let meters: Quantity<i32, si::m> = Quantity::new(5);
let millimeters: Quantity<i32, si::milli<si::m>> = meters.convert();
assert_eq!(*millimeters, 5000);

Accessing values

Quantity implements Deref, so use * to get the inner value:

use uy::{Quantity, si};

let temp: Quantity<f32, si::K> = Quantity::new(293.15);
println!("Temperature: {} K", *temp);

no_std Support

This library supports compiling in no_std environments with nightly rust using the core_float_math feature. This feature is required to perform powi operations without std.

To use this library without std, disable the default-features when depending on it. The std feature is enabled by default, which disables no_std support.

License

MIT