Pardon my tangent, is there any languages with first class, by default units support?
Not by default, but Julia has various units packages which integrate fairly well with the rest of the ecosystem. Unitful.jl [1] is the most used one I believe and integrates with DifferentialEquations.jl for example. It should also work with many other things, but you might have to patch it up a bit, especially if operations change the units (such as derivatives).