I am working on a unit-aware arithmetic library for swi-prolog (1) modeled after the c++ mp-units library (2). Turns out prolog is really well suited for this because:

* of its ability to store unit system data as code

* unit conversion is an iterative deepening depth first search

* manipulating symbolic arithmetic is so easy

Unfortunately, it requires users to compile swi-prolog for source because the library is using some unreleased features. If anyone would like to test and report some feedback, I would be truly grateful !

1. https://github.com/kwon-young/units

2. https://mpusz.github.io/mp-units/latest/