Units Domain

The Units domain brings Dimensional Analysis to your code, solving the "Mars Climate Orbiter" problem. A bare number like 10 is dangerous—is it meters? seconds? kilograms? By attaching physical units to your values, AIVI understands the laws of physics at compile time. It knows that Meters / Seconds = Speed, but Meters + Seconds is nonsense, catching bugs before they ever run.

Overview

use aivi.units (Length, Time, Velocity)

// Define values with units attached
distance = 100.0m
time = 9.58s

// The compiler knows (Length / Time) results in Velocity
speed = distance / time 
// speed is now roughly 10.43 (m/s)

Supported Dimensions

Unit = { name: Text, factor: Float }
Quantity = { value: Float, unit: Unit }

Domain Definition

domain Units over Quantity = {
  (+) : Quantity -> Quantity -> Quantity
  (+) a b = { value: a.value + b.value, unit: a.unit }
  
  (-) : Quantity -> Quantity -> Quantity
  (-) a b = { value: a.value - b.value, unit: a.unit }
  
  (*) : Quantity -> Float -> Quantity
  (*) q s = { value: q.value * s, unit: q.unit }
  
  (/) : Quantity -> Float -> Quantity
  (/) q s = { value: q.value / s, unit: q.unit }
}

Helper Functions

Function	Explanation
defineUnit name factor Text -> Float -> Unit	Creates a unit with a scale factor relative to the base unit.
convert quantity target Quantity -> Unit -> Quantity	Converts a quantity into the target unit.
sameUnit a b Quantity -> Quantity -> Bool	Returns whether two quantities share the same unit name.

Usage Examples

use aivi.units

meter = defineUnit "m" 1.0
kilometer = defineUnit "km" 1000.0

distance = { value: 1500.0, unit: meter }
distanceKm = convert distance kilometer