How do I actually use this?

I have a Haskell program that I would like to build statically with Nix. [I currently link with glibc](https://github.com/diku-dk/futhark/blob/master/default.nix), which has the usual problems, so I'm quite interested in linking with Musl instead. But while I use Nix and NixOS, I'm afraid I don't quite understand the instructions here. The only clear example I can find of how to link my own, single package against musl is [the minimal example](https://github.com/nh2/static-haskell-nix/blob/master/default.nix), which I am told not to use in practice. Apart from that, the documentation points me at [survey/default.nix](https://github.com/nh2/static-haskell-nix/blob/master/survey/default.nix), which is a 1300 line .nix file, and encourages me to "easily import this functionality and add an override to add your own packages". I've tried reading the code, but I'm afraid I have no idea what is going on, or how to make use of it.

Is there a simple example of how to use this somewhere?