I've done that for a number of languages (ruby, python, perl, java, haskell, elm, c, erlang, lua, tcl, etc.) and their inevitable "yet another package manager"

I've done that for a number of languages (ruby, python, perl, java, haskell, elm, c, erlang, lua, tcl, etc.) and their inevitable "yet another package manager" via nix. Making them all use hashed fixed input sources without allowing any networking or file access during their build and install phases brings me great joy. That's not only useful for deployment but also so you don't end up with development environments that have subtle differences. This enables me to focus more on my developer job. Getting things done faster and with confidence. I'm sure at some point, just like with programming languages, people will start to ask for more immutability and reproducibility in their OS as well.