Converting from m/s to km/h using F# Units of Measure

Question

I\'m in the process of learning F# - and is currently looking into Units of Measure. I have a simple calculation returning meters per second, and I want to introduce a function

Answer 1

You're right that removing unit information is a bad thing. You should create a few constants with appropriate units for conversion.

let mPerKm = 1000.0
let secondPerHour = 3600.0

// val msToKmph : float -> float
let msToKmph(speed : float) =
    speed / mPerKm * secondPerHour

For km and m, a generic solution is to define a unit prefix k so it works for many UoMs which have kilo as a metric:

[] type k

let kilo = 1000.0<1/k>
let secondPerHour = 3600.0

// val msToKmph : float -> float
let msToKmph(speed : float) =
    speed / kilo * secondPerHour