dim is a dimensional analysis and unit conversion library for Zig, with an optional CLI tool for quick calculations.
I was inspired by the syntax used in Julia by Unitful and DynamicQuantities, where you can define a quantity by simply writing the value and its unit string.
0.2u"m/s"This felt much better than an approach I had used at work, where we had to use the constructor for the type of quantity we want to create and then also specify the unit
new Speed(0.2, SpeedUnits.MetersPerSecond);It is useful to know the type of quantity, so you can make sure you only do valid operations with your values, but that can be determined by the unit string.
Having a constructor for every type of quantity and an enum for all the units for that quantity feels bad.
I think a better approach is to use base units and define how they interact. I defined the dimensions for the base quantities and common derived quantities and also how these dimensions are combined when you add/subtract/multiply/divide quantities.
Knowing that an area has a dimension of L=2 and a length has L=1 means you can add the dimensions together when you multiply them to produce a volume with L=3.
This means that you don’t need to explicitly write code for each operation on two quantities: a distance divided by a time will produce a speed; a force divided by an area will produce a pressure.
And every possible combination of units works. I don’t need to know the distance in meters and the time in seconds so I can use the Speed constructor with the SpeedUnits.MetersPerSecond enum. I can create a speed by using the unit string "yd/h" if I need to.