With the arrival of Corepack I'm no longer installing yarn from Homebrew, and have no more need of this project. I think the stdenv concept is still useful & so this project is archived for you to fork & modify to your needs.
Tap of Homebrew formulae modified to use the standard environment & look for non-Homebrew dependency fulfillment.
brew install gfguthrie/stdenv/<formula>Want to see something added here? Create an issue!
Or create a pull request if you have code you'd like to contribute.