use core::scalar
use core::error

@description("Extract the plain value of a quantity (the `20` in `20 km/h`). This can be useful in generic code, but should generally be avoided otherwise.")
@example("value_of(20 km/h)")
fn value_of<T: Dim>(x: T) -> Scalar

@description("Extract the unit of a quantity (the `km/h` in `20 km/h`). This can be useful in generic code, but should generally be avoided otherwise. Returns an error if the quantity is zero.")
@example("unit_of(20 km/h)")
fn unit_of<T: Dim>(x: T) -> T = if x_value == 0 then error("…") else x / value_of(x)
    where x_value = value_of(x)