If you feel lost in a world of
nix and darwin operating systems, unsure of what is
pure and impure remember this always:
Your cpu will only execute streams of instructions and these instructions are stored as numbers somewhere in your computers memory.
Those instructions are stored somewhere! So all you need to do is find out where they are and how to get your code to point them.
If all seems at a loss with building in darwin remember this principle! There is always a way to build, patch, overlay, and find all the binaries you need. And nix will help you do it.