[saghm]

> it still requires...a working installation of Ruby.

Does OS X/macOS not still come with a bundled installation of Ruby? Or is the version it comes with too old to use with brew/brew cask?

[neon_electro]

I believe it does, but I don't usually use it; rather, I usually get Ruby Version Manager to manage one or more Ruby runtimes on my Mac. Therefore I can't vouch for it to work with brew and/or brew cask.