si

NOTE: this is still a work in progress

si is a unit annotation and conversion library. Its different from other strongly typed si/unit libraries in the way that all types are aliases to float64 instead of concrete types. The benefit of this approach is that casting can be avoided which results in more readable code that somewhat resembles the math equation.

To prove my point i have created an example using Einstein's mass-energy equivalence formular $E=mc^2$.

// possible using aliased si types
24.965421631578266*MWh == 1*mg * math.Pow(c, 2)

// problem with conrete si types...
24.965421631578266*MWh == MWh(float64(1*mg) * math.Pow(c, 2))

As it can be seen in the example above casting ends up hurting readability and it really doesn't add anything in terms of type safety because casting will be so prevalent. It will only be as safe as the aliased approach used in this library.

Another benefit is that derived si types can easily be defined on the fly, this is not possible when using concrete types unless casting is involved.

const SpeedOfLight = 299792458 * (Meter/Second)

It will also work well with the math package from standard lib or any other thirdparty library which is using float64 as input or output types. Below is an example of how it could be used with a vector package.

Vector{10 * (Meter/Second)}.Rotate(45*Degree)

Install

go get github.com/quartercastle/si

Usage

func MassEnergyEquivalence(energy si.Energy, mass si.Mass) bool {
  return energy == mass * math.Pow(si.SpeedOfLight, 2)
}


MassEnergyEquivalence(24.965421631578266*si.MegawattHour, 1*si.Milligram)

Credits

This project is heavily inspired by github.com/martinlindhe/unit, which is a strongly typed unit conversion library that i have used a lot previously. It would not exist without the knowledge i have gained by using this library.

License

This project is licensed under the MIT License.