homebrew formula

zero-install.rb

require 'formula'

class ZeroInstall < Formula
  homepage 'http://0install.net/injector.html'
  url 'https://downloads.sf.net/project/zero-install/0install/2.6.2/0install-2.6.2.tar.bz2'
  sha256 '5755226ef4b32f04723bcbe551f4694ddf78dffbb0f589c3140c2d7056370961'

  head 'https://github.com/0install/0install'

  option 'without-gui', "Build without the gui (requires GTK+)"

  depends_on 'gnupg'
  depends_on 'glib' if build.without? 'gui'
  depends_on 'gtk+' if build.with? 'gui'
  depends_on 'gettext' => :build if build.head?

  depends_on 'objective-caml' => :build
  depends_on 'opam' => :build

  def install
    modules = "yojson xmlm ounit react lwt extlib ssl ocurl"
    modules += " lablgtk" if build.with? 'gui'

    # TODO: Use $OPAMCURL to store a cache outside the build directory
    ENV['OPAMCURL'] = "curl"

    ENV['OPAMROOT'] = "opamroot"
    system "opam init --no-setup"
    ENV['OPAMYES'] = "1"
    system "eval \`opam config env\`; opam install #{modules}"

    system "make"
    system "cd dist && ./install.sh #{prefix}"
  end
end

I've made some build fixes (notably deparallelise, lablgtk2 build fixes, and use opam config exec to run make) in my fork: https://gist.github.com/avsm/39d0ced39f9ed45165d5

Are you planning to submit this upstream to Homebrew?

Submitted upstream with a patch to fix installation in Homebrew/legacy-homebrew#28806