You can find it at https://github.com/happenslol/qwer . Be warned though, it's heavily lacking in documentation and polish, although all core features are working. I've just added a bit of info to the Readme, hit me up if you have any questions.
This looks really promising. I love seeing these tools written in languages other than the thing they're targeting.
As an example I use fnm (https://github.com/Schniz/fnm) for managing JavaScript versions. It runs so fast (compared to nvm) I'm inclined to think something went wrong and it silently failed, but it never does!
This is really cool! You're pretty much solving all the issues I've had with asdf! Keep up the great work!