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Units and dimensions

All quantities use typed uom::si::f64 values. All dimensions are listed below:

Dimension Literal spellings Rust type / serde adapter
Length SI-prefixed metres (ym–Ym, including um/µm/μm), ft, in, mi, yd, and astronomical units Length / length
Time SI-prefixed seconds (ys–Ys, including us/µs), min, h, d, and a Time / time
Mass SI-prefixed grams (yg–Yg, including ug/µg, mg, g, kg), t/tonne/tonnes, lb/pound/pounds, oz/ounce/ounces Mass / mass
Angle deg, rad, mrad, urad, µrad Angle / angle
Frequency mHz, Hz, kHz, MHz, GHz Frequency / frequency
Velocity mm/s, cm/s, m/s, km/h Velocity / velocity
Acceleration mm/s2, cm/s2, m/s2 (also /s^2) Acceleration / acceleration 
# Lunar rover, landing site Shackleton rim.

# @type angle
# @min 0deg
# @max 180deg
camera.field_of_view = 90deg
mast.pan_resolution = 500urad

# @type frequency
# @min 1Hz
imu.rate = 2kHz

# 0.54km/h and 0.15m/s are the same speed.
# @type velocity
# @max 0.2m/s
drive.top_speed = 0.54km/h

# The Moon pulls a sixth as hard.
# @type acceleration
gravity = 1.62m/s2

# @type mass
# @min 500g
# @max 5kg
arm.payload = 2kg
sample_mass = 250mg
regolith_scoops = [20g, 35g, 50g]
allowed_payload = 500g..5kg
lander = 1.5t
souvenir = 2lb

These values work in arrays, matrices, ranges, constraints, and schema completion/hover. Bounds compare across units while rejecting mismatched dimensions. With serde enabled, use Quantity<Mass>, Quantity<Angle>, Quantity<Frequency>, Quantity<Velocity>, or Quantity<Acceleration>, or attach the corresponding ratslang::serde field adapter to a direct uom field. Serialization chooses readable units. It may normalize degrees to radians or km/h to m/s.

For direct uom fields, the same adapters work in both directions:

use ratslang::{Mass, kilogram};
use ratslang::serde::Quantity;
use serde::{Deserialize, Serialize};

#[derive(Serialize, Deserialize)]
struct Payload {
    #[serde(with = "ratslang::serde::mass")]
    maximum: Mass,
    samples: Vec<Quantity<Mass>>,
}
let payload: Payload = ratslang::from_str(
    "maximum = 2kg\nsamples = [250mg, 1g, 5ug]\n",
)?;
assert_eq!(payload.maximum.get::<kilogram>(), 2.0);
let source = ratslang::to_string(&payload)?;

Time and length spellings

Time accepts SI-prefixed seconds, min/minute/minutes, h/hour/hours, d/day/days, a/year/years, shake/shakes, sidereal variants such as second_sidereal, and year_tropical. Use 2min, rather than 2mins.

Length also accepts feet, inches, yards, miles, chains, rods, fathom, angstrom/Å, micron/µ, mil, microinch, bohr_radius, fermi, au/ua/astronomical_unit, light_year/l.y., pc, and nautical_mile. Plural word forms are accepted where declared by the lexer. Spellings are case-sensitive: mHz and MHz differ by a factor of a billion.

Serialization selects readable units while preserving the underlying SI value. For example, small lengths may become um and a mass may become 250mg. Use types re-exported by Ratslang (or ratslang::uom) to keep the same uom version as the library.