After reading the landing page I’m still unsure what this project is about. What would definitely help me are some examples on the page, because the given example is without much annotations.
From what I can tell from the docs and source code, the idea seems to be a language independent CLI parsing library. Essentially, you write a nix script that identifies all your sub commands, flags, and positional parameters. It then generates a Bash script which handles all the command line parsing and validation and runs the correct executable.
Some things like allowing a CLI to default back to a certain environment variable is a nice touch that isn’t present in every CLI parsing libarry. I can also imagine that it would be about the only sane option if you have multiple utilities written in different languages that you want to expose behind a single subcommand interface.
Again, though, this is based on a five minute skim of the code.
BTW I was doing some module work to allow polyglot codegen, so far it only generates shell script but implementing more languages should be trivial, your own code could be readFiled to the prelude then it generates your main function for C for example. I might move some target options to somewhere else.