I'm almost halfway through this: https://plfa.github.io/ https://plfa.github.io/ I was auditing a grad class at UT that used this book, then corona hit. Still

I'm almost halfway through this: https://plfa.github.io/ https://plfa.github.io/ I was auditing a grad class at UT that used this book, then corona hit. Still plan to finish it eventually though I'm not even really sure where I would get started working on an implementation or working on a paper. Are these projects open source?