Nix is the ultimate DevOps toolkit(tech.channable.com)

    let pkgs = import <nixpkgs> {}; in
    pkgs.runCommand "my-app"
      {
        buildInputs = [pkgs.ruby];
      }
      ''
        pwd && ls
        ruby ${./program.rb}
      ''

    let pkgs = import <nixpkgs> {}; in
    pkgs.runCommand "my-app"
      {
        buildInputs = [pkgs.ruby];
        program = ./program.rb;
      }
      ''
        pwd && ls;
        ruby "$program"
      ''

    with { foo = 1; };
    with { foo = 2; };
    with { foo = 3; };
    with { bar = with { foo = 4; }; foo; };
    [ foo bar ]

    with {
      f = foo: with { foo = 42; }; foo;
    };
    f 123

    foo:
      with bar;
      x + foo